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FITTER, NSQF LEVEL - 5, , 1st Year (Volume I of II), , TRADE THEORY, SECTOR: Production & Manufacturing, , DIRECTORATE GENERAL OF TRAINING, MINISTRY OF SKILL DEVELOPMENT & ENTREPRENEURSHIP, GOVERNMENT OF INDIA, , NATIONAL INSTRUCTIONAL, MEDIA INSTITUTE, CHENNAI, (i) Guindy, Chennai - 600 032, Post Box No. 3142, CTI Campus,, , Copyright Free Under CC BY Licence
Page 2 : Sector, , : Production & Manufacturing, , Duration : 2 - Years, Trade, , : Fitter 1st Year (volume I of II) - Trade Theory - NSQF LEVEL - 5, , First Edition, Second Edition, , :, :, , August 2018, November 2018, , Copies : 1,000, Copies : 10,000, , Rs. 295/-, , All rights reserved., No part of this publication can be reproduced or transmitted in any form or by any means, electronic or mechanical, including, photocopy, recording or any information storage and retrieval system, without permission in writing from the National, Instructional Media Institute, Chennai., , Published by:, NATIONAL INSTRUCTIONAL MEDIA INSTITUTE, P. B. No.3142, CTI Campus, Guindy Industrial Estate,, Guindy, Chennai - 600 032., Phone : 044 - 2250 0248, 2250 0657, 2250 2421, Fax : 91 - 44 - 2250 0791, email :
[email protected],
[email protected], Website: www.nimi.gov.in, (ii), , Copyright Free Under CC BY Licence
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FOREWORD, The Government of India has set an ambitious target of imparting skills to 30 crores people, one out of every, four Indians, by 2020 to help them secure jobs as part of the National Skills Development Policy. Industrial, Training Institutes (ITIs) play a vital role in this process especially in terms of providing skilled manpower., Keeping this in mind, and for providing the current industry relevant skill training to Trainees, ITI syllabus, has been recently updated with the help of Mentor Councils comprising various stakeholder's viz. Industries,, Entrepreneurs, Academicians and representatives from ITIs., The National Instructional Media Institute (NIMI), Chennai, has now come up with instructional material to, suit the revised curriculum for Fitter 1st Year (volume I of II) Trade Theory NSQF Level - 5, in Production & Manufacturing Sector under Semester Pattern. The NSQF Level - 5 Trade Theory, will help the trainees to get an international equivalency standard where their skill proficiency, and competency will be duly recognized across the globe and this will also increase the, scope of recognition of prior learning. NSQF Level - 5 trainees will also get the opportunities to, promote life long learning and skill development. I have no doubt that with NSQF Level - 5 the trainers, and trainees of ITIs, and all stakeholders will derive maximum benefits from these IMPs and that NIMI's, effort will go a long way in improving the quality of Vocational training in the country., The Executive Director & Staff of NIMI and members of Media Development Committee deserve appreciation, for their contribution in bringing out this publication., Jai Hind, , RAJESH AGGARWAL, , Director General/ Addl. Secretary, Ministry of Skill Development & Entrepreneurship,, Government of India., , New Delhi - 110 001, , (iii), , Copyright Free Under CC BY Licence
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PREFACE, The National Instructional Media Institute (NIMI) was established in 1986 at Chennai by then Directorate, General of Employment and Training (D.G.E & T), Ministry of Labour and Employment, (now under Ministry, of Skill Development and Entrepreneurship) Government of India, with technical assistance from the Govt., of the Federal Republic of Germany. The prime objective of this institute is to develop and provide instructional, materials for various trades as per the prescribed syllabi under the Craftsman and Apprenticeship Training, Schemes., The instructional materials are created keeping in mind, the main objective of Vocational Training under, NCVT/NAC in India, which is to help an individual to master skills to do a job. The instructional materials are, generated in the form of Instructional Media Packages (IMPs). An IMP consists of Theory book, Practical, book, Test and Assignment book, Instructor Guide, Audio Visual Aid (Wall charts and Transparencies) and, other support materials., The trade practical book consists of series of exercises to be completed by the trainees in the workshop., These exercises are designed to ensure that all the skills in the prescribed syllabus are covered. The trade, theory book provides related theoretical knowledge required to enable the trainee to do a job. The test and, assignments will enable the instructor to give assignments for the evaluation of the performance of a trainee., The wall charts and transparencies are unique, as they not only help the instructor to effectively present a, topic but also help him to assess the trainee's understanding. The instructor guide enables the instructor to, plan his schedule of instruction, plan the raw material requirements, day to day lessons and demonstrations., In order to perform the skills in a productive manner instructional videos are embedded in QR code of the, exercise in this instructional material so as to integrate the skill learning with the procedural practical steps, given in the exercise. The instructional videos will improve the quality of standard on practical training and, will motivate the trainees to focus and perform the skill seamlessly., IMPs also deals with the complex skills required to be developed for effective team work. Necessary care, has also been taken to include important skill areas of allied trades as prescribed in the syllabus., The availability of a complete Instructional Media Package in an institute helps both the trainer and, management to impart effective training., The IMPs are the outcome of collective efforts of the staff members of NIMI and the members of the Media, Development Committees specially drawn from Public and Private sector industries, various training institutes, under the Directorate General of Training (DGT), Government and Private ITIs., NIMI would like to take this opportunity to convey sincere thanks to the Directors of Employment & Training, of various State Governments, Training Departments of Industries both in the Public and Private sectors,, Officers of DGT and DGT field institutes, proof readers, individual media developers and coordinators, but for, whose active support NIMI would not have been able to bring out this materials., , R. P. DHINGRA, EXECUTIVE DIRECTOR, , Chennai - 600 032, , (iv), , Copyright Free Under CC BY Licence
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INTRODUCTION, TRADE THEORY, The manual of trade theory consists of theoretical information for the first semester course of the Fitter Trade., The contents are sequenced according to the practical exercise contained in NSQF LEVEL - 5 syllabus on Trade, Practical. Attempt has been made to relate the theoretical aspects with the skill covered in each exercise to, the extent possible. This correlation is maintained to help the trainees to develop the perceptional capabilities, for performing the skills., The trade theory has to be taught and learnt along with the corresponding exercise contained in the manual on, trade practical. The indications about the corresponding practical exercises are given in every sheet of this, manual., It will be preferable to teach/learn trade theory connected to each exercise at least one class before performing, the related skill in the shop floor. The trade theory is to be treated as an integrated part of each exercise., The material is not for the purpose of self-learning and should be considered as supplementary to class room, instruction., TRADE PRACTICAL, The trade practical manual is intended to be used in practical workshop. It consists of a series of practical, exercises to be completed by the trainees during the First Semester course of Fitter Trade supplemented and, supported by instructions / informations to assist in performing the exercises. These exercises are designed, to ensure that all the skills in compliance with NSQF LEVEL - 5 syllabus are covered., The manual is divided into four modules. The distribution of time for the practical in the four modules are given below:, Module 1, , Safety, , 25 Hrs, , Module 2, , Basic Fitting, , 275 Hrs, , Module 3, , Sheet Metal, , 150 Hrs, , Module 4, , Welding, , 100 Hrs, , Total, , 550 Hrs, , The skill training in the shop floor is planned through a series of practical exercise centered around some, practical object. However, there are few instances where the individual exercise does not from a part of project., While developing the practical manual, a sincere effort was made to prepare each exercise which will be easy to, understand and carry out even by below average traninee. However the development team accept that there is a, scope for further improvement. NIMI looks forward to the suggestions from the experienced training faculty for, improving the manual., , (vi), , Copyright Free Under CC BY Licence
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CONTENTS, Lesson No., , Title of the Lesson, , Page No., , Module 1 : Safety, 1.1.01, , Safety, , 1, , Familiar with the working of Industrial Training Institute system including, stores procedures, 1.1.02, , 2, , Importance of safety and general precautions observed in the industry/shop, floor, , 3, , Approach on soft skills, , 4, , Personal Protective Equipment (PPE), , 5, , 1.1.03, , First-aid, , 9, , 1.1.04, , Guidelines for good shop floor maintenace, , 14, , Importance of housekeeping, , 15, , Disposal of waste material, , 15, , 1.1.05, , Occupational health and safety, , 17, , 1.1.06, , Safety Sign, , 19, , Safety practice, , 21, , Response to emergencies - Power failure, System failure & Fire, , 23, , Reporting emergecy, , 23, , Operation of electrical mains/ Circuit breakers and electrical safety, , 25, , Area of control of switches - operation on emergency, , 27, , Safety rules on electrical equipments, , 28, , Safety practice - fire extinguishers, , 29, , Types of fire extinguishers, , 31, , Working on fire extinguishers, , 32, , 1.1.09, , Safety, Health and Environment Guidelines, , 35, , 1.1.10, , Basic understanding on Hot work, Confined space work and material handing, equipment, , 37, , Lifting and handling loads, , 37, , Moving heavy equipment, , 39, , 1.1.07, , 1.1.08, , Module 2 : Basic Fitting, 1.2.11, , Linear measurement, , 43, , 1.2.12, , Scribers, , 45, , Dividers, , 45, , Datum, , 46, , Calipers, , 47, , Jenny calipers, , 47, , 1.2.13, , (vii), , Copyright Free Under CC BY Licence
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Lesson No., 1.2.14, , Title of the Lesson, , Page No., , Types of marking punches, , 49, , Hammers, , 49, , ‘V’ Blocks, , 51, , Marking off and marking off table, , 52, , Bench vice, , 53, , Hacksaw frames and blades, , 54, , 1.2.16, , Types of vices, , 56, , 1.2.17, , Try square, , 58, , Elements of a file, , 59, , Cut of files, , 60, , File specifications and grades, , 61, , Types of files, , 62, , Needle files, , 63, , Special files, , 64, , Pinning of files, , 65, , Care and maintenance, , 65, , Convexity of files, , 66, , Measurements of angles, , 67, , Angular measuring instruments (Semi - precision), , 68, , Combination set, , 68, , Measuring standards (English & metric), , 69, , 1.2.20, , Surface gauges, , 71, , 1.2.21, , Cold Chisel, , 73, , Angles of chisels, , 74, , Ordinary depth gauge, , 75, , 1.2.22, , Sharpening of Chisels, , 76, , 1.2.23, , Marking media, , 78, , 1.2.24, , Surface plates, , 79, , 1.2.25, , Angle plates, , 80, , Parallel blocks, , 81, , 1.2.26-30, , Physical and mechanical properties of metals, , 83, , 1.2.31, , Power hacksaw, , 86, , 1.2.32, , Metal-cutting saws, , 88, , 1.2.33, , Outside micrometer, , 90, , Reading dimensions with outside micrometer, , 91, , Constructional features of outside micrometer, , 92, , Inside micrometer, , 93, , 1.2.15, , 1.2.18, , 1.2.19, , (viii), , Copyright Free Under CC BY Licence
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Lesson No., , 1.2.34, , 1.2.35, , 1.2.36, , 1.2.37, , 1.2.38, , 1.2.39, , 1.2.40- 41, , Title of the Lesson, , Page No., , Depth micrometer, , 96, , Digital micrometers, , 97, , Vernier calipers, , 99, , Graduations and reading of vernier calipers, , 100, , The british system of measurement, , 101, , Reading vernier caliper and micrometer with inch graduations, , 101, , Vernier height gauge, , 103, , Vernier bevel protractor, , 106, , Graduations on universal bevel protractor, , 107, , Reading of universal bevel protractor, , 108, , Dial Caliper, , 109, , The digital caliper, , 110, , Drilling processes - Drilling Machines, Types, Use and Care, , 111, , Drill - Holding devices, , 112, , Work-holding devices, , 113, , Cutting speed and RPM, , 114, , Feed in drilling, , 115, , Radial drilling machines, , 116, , Gang drilling machine and multiple spindle head drilling machine, , 117, , Hand taps and wrenches, , 118, , Tap drill size, , 119, , Letter punch and number punch, , 122, , Module 3 : Sheet Metal, 1.3.42, , Safety precautions in sheet metal workshop, , 123, , 1.3.43, , Metal sheets and their uses, , 129, , 1.3.44, , Hand lever shears, , 134, , 1.3.45 - 1.3.47, , Sheet Metal Tools, , 139, , 1.3.48, , Stakes and their uses, , 166, , 1.3.49, , Sheet metal seams, , 170, , 1.3.50 -1.3.51, , Solders, , 184, , 1.3.52 -1 .3.55, , Rivets and riveting, , 195, , Module 4 : Welding, 1.4.56, , Safety, , 209, , 1.4.57 - 1.4.58, , Welding hand tools, , 224, , 1.4.59, , Setting up parameter for arc welding machine, , 255, , 1.4.60, , Safety precautions in handling gas cutting plant, , 268, , (ix), , Copyright Free Under CC BY Licence
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LEARNING/ ASSESSABLE OUTCOME, On completion of this book you shall be able to, • Recognise & Comply Safe working Practices, environment regulation and house keeping, • Plan and Organize the work to make job as per specification, applying different types of basic fitting operation and check for, dimensional accuracy. (Basic fitting operation - marking, hacksawing,, chiseling, filing, drilling, taping and grinding etc., Accuracy, ± 0.25mm), • Manufacture Simple Sheet Metal items as per drawing and join them, by soldering, brazing and riveting., • Join Metal Components by arc welding observing standard, procedure., • Cut and Join Metal Component by gas (Oxy-acetylene), • Cut and Join Metal Component by gas (Oxy-acetylene) & Join Metal, components by riveting observing standard procedure., , (x), , Copyright Free Under CC BY Licence
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SYLLABUS, 1st Year (volume I of II), Week, No., 1., , 2., , Ref. Learning, Outcome, •, , Recognize &, comply, safe working, practices,, environment, regulation and, housekeeping, , • Plan and organize, , the work to make job, as per specification, applying different, types of basic fitting, operations & check, for dimensional, accuracy. [Basic, Fitting Operation –, Marking, Hack, sawing, filing drilling,, taping etc.], , Duration: Six Month, Professional Skills, (Trade Practical), with Indicative hours, , Professional Knowledge, (Trade Theory), , 1., , Importance of trade training, List, of tools & Machinery used in the, trade.(1 hrs.), 2. Safety attitude development of, the trainee by educating them to, use Personal Protective, Equipment (PPE). (5 hrs.), 3. First Aid Method and basic, training.(2 hrs.), 4. Safe disposal of waste materials, like cotton waste, metal, chips/burrs etc. (2 hrs.), 5. Hazard identification and, avoidance. (2 hrs.), 6. Safety signs for Danger,, Warning, caution & personal, safety message.(1 hrs.), 7. Preventive measures for, electrical accidents & steps to, be taken in such accidents.(2, hrs.), 8. Use of Fire extinguishers.(7 hrs.), 9. Practice and understand, precautions to be followed while, working in fitting jobs. (2 hrs.), 10. Safe use of tools and, equipments, used in the trade. (1 hrs.), , All necessary guidance to be, provided to, the new comers to become, familiar with, the working of Industrial Training, Institute system including stores, procedures., Soft Skills: its importance and, Job area, after completion of training., Importance of safety and general, precautions observed in the in, the, industry/shop floor., Introduction of First aid., Operation of, electrical mains. Introduction of, PPEs., Response to emergencies e.g.;, power, failure, fire, and system failure., Importance of housekeeping &, good, shop floor practices., Introduction to 5S, concept & its application., Occupational Safety & Health:, Health,, Safety and Environment, guidelines,, legislations & regulations as, applicable, , 11. Identification of tools, &equipments as per desired, specifications for marking &, sawing. (5 hrs.), 12. Selection of material as per, application.(1 hrs.), 13. Visual inspection of raw, material for rusting, scaling,, corrosion etc.(1 hrs.), 14. Marking out lines, gripping, suitably in vice jaws,, hacksawing to given, dimensions. (10 hrs.), 15. Sawing different types of, metals of different sections., (8 hrs.), , Linear measurements- its units,, dividers, calipers,, hermaphrodite, centre punch,, dot punch, their description and, uses of different types of, hammers. Description, use and, care of „V. Blocks, marking off, table., , Copyright Free Under CC BY Licence
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3, , -do-, , 16. Filing Channel, Parallel. (5, hrs.), 17. Filing- Flat and square, (Rough finish), (10 hrs.), 18. Filing practice, surface filing,, marking of straight and, parallel lines with odd leg, calipers and steel rule. (5, hrs.), 19. Marking practice with, dividers,odd leg calipers and, steel rule (circles, ARCs,, parallel lines). (5 hrs.), , Bench vice construction, types, uses,, care & maintenance, vice clamps,, hacksaw frames and blades,, specification, description, types and, their uses, method of using, hacksaws., Files- specifications, description,, materials, grades, cuts, file elements,, uses. Types of files, care and, maintenance of files., Measuring standards (English, Metric, Units), angular measurements., , 4, , -do-, , 20. Marking off straight lines, and ARCs using scribing, block and dividers. (5 hrs.), 21. Chipping flat surfaces, along a marked line. (10, hrs.), 22. Marking, filing, filing, square and check using trisquare.(10 hrs.), , Marking off and layout tools,, dividers, scribing block, odd leg, calipers, punchesdescription,, classification, material, care, & maintenance., Try square, ordinary depth gauge,, protractor- description, uses and, cares., Calipers- types, material,, constructional details, uses, care &, maintenance of cold chisels, materials, types, cutting angles., , 5-6, , -do-, , 23. Marking according to simple, blue prints for locating, position, of holes, scribing lines on, chalked surfaces with marking, tools. (20 hrs.), 24. Finding center of round bar, with the help of „V. block and, marking block. (5 hrs.), 25. Joining straight line to an, ARC.(25 hrs.), , Marking media, marking blue,, Prussian blue, red lead, chalk and, their special application,, description., Use, care and maintenance of, scribing block., Surface plate and auxiliary marking, equipment, „V. block, angle plates,, parallel block, description, types,, uses, accuracy, care and, maintenance., , 7-8, , -do-, , 26. Chipping, Chamfering, Chip, slots & oils grooves, (Straight).(10 hrs.), 27. Filing flat, square, and parallel, to an accuracy of 0.5mm. (10, hrs.), 28. Chip curve along a line-mark, out, key ways at various, angles & cut key ways.(15, hrs.), 29. Sharpening of Chisel.(5 hrs.), 30. File thin metal to an accuracy, of 0.5 mm.(10 hrs.), , Physical properties of engineering, metal: colour, weight, structure, and, conductivity, magnetic, fusibility,, specific gravity. Mechanical, properties: ductility, malleability, hardness, brittleness, toughness,, tenacity, and elasticity., , Copyright Free Under CC BY Licence
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9, , 10, , -do-, , -do-, , 11, , -do-, , 12, , -do-, , 13, , 14-15, , 16, , Manufacture simple, sheet metal items, as per drawing and, join them by, soldering, brazing, and riveting., , -do-, , -do-, , 31. Saw along a straight line, curved, line, on different sections of, metal.(15 hrs.), 32. Straight saw on thick section, M.S., angle and pipes.(10 hrs.), , Power Saw, band saw, Circular, saw machines used for metal, cutting., , 33. File steps and finish with smooth, file to accuracy of ± 0.25 mm., (10 hrs.), 34. File and saw on M.S. Square, and pipe. (5 hrs.), , Micrometer- outside and inside –, principle, constructional features,, parts graduation, leading, use and, care., Micrometer depth gauge, parts,, graduation, leading, use and care., Digital micrometer., , 35. File radius along a marked line, (Convex & concave) & match., (15 hrs.), 36. Chip sheet metal (shearing)., (5 hrs.), 37. Chip step and file. (5 hrs.), , Vernier calipers, principle,, construction, graduations, reading,, use and care., Vernier bevel protractor,, construction, graduations, reading,, use and care, dial Vernier Caliper,, Digital verniercaliper., , 38. Mark off and drill through holes., (5 hrs.), 39. Drill and tap on M.S. flat. (10, hrs.), 40. Punch letter and number (letter, punch and number punch) (5, hrs.), 41. Practice use of different, punches.(5 hrs.), , Drilling processes: common type, (bench type, pillar type, radial, type), gang and multiple drilling, machine., Determination of tap drill size., , 42. Marking of straight lines,, circles, profiles and various, geometrical shapes and cutting, the sheets with snips. (15 hrs.), 43. Marking out of simple, development (5 hrs.), 44. Marking out for flaps for, soldering and sweating.(5 hrs.), , Safety precautions to be, observed in a sheet metal, workshop, sheet and sizes,, Commercial sizes and various, types of metal sheets, coated, sheets and their uses as per BIS, specifications. Shearing machinedescription, parts and uses., , 45. Make various joints: wiring,, hemming, soldering and, brazing, form locked, grooved, and knocked up single hem, straight and curved edges form, double hemming,.(15hrs.), 46. Punch holes-using hollow and, solid punches. (2 hrs.), 47. Do lap and butt joints.(8 hrs.), , Marking and measuring tools,, wing compass, Prick punch, tin, man.s square tools, snips, types, and uses. Tin man.s hammers, and mallets type-sheet metal, tools, Soldering iron, types,, specifications, uses., Trammeldescription, parts, uses., Hand grooves specifications, and uses., , 48. Bend sheet metal into, various curvature form,, wired edgesstraight and, curves. Fold sheet, metal at angle using, stakes. (8 hrs.), , Stakes-bench types, parts, their, uses. Various types of metal joints,, their selection and application,, tolerance for various joints, their, selection & application. Wired, edges., , Copyright Free Under CC BY Licence
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49. Make simple Square container, with wired edge and fix, handle.(17 hrs.), 50. Make square tray with square, soldered corner.(15 hrs.), 51. Practice in soft soldering and, silver soldering. (10 hrs.), , Solder and soldering: Introductiontypes of solder and flux. Composition, of various types of solders and their, heating media of soldering iron., Method of soldering, selection and, application joints., Hard solder- Introduction, types, and method of brazing., , Join metal, component by, arc welding, observing, standard, procedure., , 52. Make riveted lap and butt, joint.(9 hrs.), 53. Make funnel as per, development and solder, joints.(10 hrs.), 54. Drill for riveting. (1 hrs.), 55. Riveting with as many types, of rivet as available, use of, counter sunk head rivets. (5, hrs.), , Various rivets shape and form of, heads,importance of correct head, size., Rivets-Tin man.s rivets types, sizes,, and selection for various works., Riveting tools, dolly snaps description, and uses. Method of riveting,, The spacing of rivets. Flash riveting,, use of correct tools, compare hot and, cold riveting., , 19, , Cut and join, metal, component by, gas (oxyacetylene), , 56. Welding - Striking and, maintaining ARC, laying, Straightline bead.(25 hrs.), , Safety-importance of safety and, general precautions observed in a, welding shop., Precautions in electric and gas, welding. (Before, during, after), Introduction to safety equipment, and their uses. Machines and, accessories, welding transformer,, welding generators., , 20, , Cut and join metal, component by gas, (oxy-acetylene), & Join metal, components by, riveting observing, standard, procedure., , 57. Making square, butt joint and, „T. fillet joint-gas and ARC. (15, hrs.), 58. Do setting up of flames, fusion, runs with and without filler rod,, and gas.(10 hrs.), , Welding hand tools: Hammers,, welding description, types and uses,, description, principle, method of, operating, carbon dioxide welding., H.P. welding, equipment: description,, principle,method of operating L.P., welding, equipment: description, principle,, method of operating. Types of JointsButt and fillet as per BIS SP: 46-1988, specifications. Gases and gas cylinder, description, kinds, main difference and, uses., , 17, , 18, , -do-, , 21, , Cut and join metal, component by gas, (oxy-acetylene), , 59. Make butt weld and corner, fillet, in ARC welding(25 hrs.), , Setting up parameters for ARC, welding machines-selection of, Welding electrodes. Care to be, taken in keeping electrode., , 22, , Join metal, components by, riveting observing, standard, procedure., , 60. Gas cutting of MS, plates(25 hrs.), , Oxygen acetylene cutting-machine, description, parts, uses, method of, handling, cutting torch-description,, parts, function and uses., , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.01, , Familiar with industrial training institute, Objectives: At the end of this lesson you shall be able to, • explain about DGT affiliated institutions under MSDE, • familiarise with working of ITI using organisational chart of ITI, • state the function of store procedures in training institutes., Introduction, , Training Institutes under DGT, , Directorate General of Training (DGT), , • 13350 Industrial Training institutes (ITIs), , Directorate General of Training (DGT) in Ministry of Skill, Development & Entrepreneurship is an apex organization, for development and coordination of the vocational training, including Women's Vocational Training of the employable, youth in the country and to provide skilled manpower to, the economy., , • 31 Central Institutes, , Two verticals of Directorate General of Employment &, Training (DGE&T) working under Deputy Director General, (Training) & Deputy Director General (Apprenticeship, Training ) along with their support systems were transferred, to Ministry of Skill Development & Entrepreneurship, (MSDE)., , • 2 Foremen Training Institutes (FTIs), , DGT affiliated institutions offers a wide range of training, courses catering to the needs of different segments in the, Labour market. Courses are available for school leavers,, ITI pass outs, ITI instructors, industrial workers,, technicians, junior and middle level executives,, supervisors/foremen, women, physically disabled persons, and SC/STs., It also conducts training oriented research and develops, instructional media packages for the use of trainees and, instructors etc., , • 10 Advanced Training Institutes (ATIs), • 2 ATI-EPIs (Advanced Training Institutes - Electronic, Process Instrumentation), , • 1 Central Training Institutes (CTI), • 1 National Vocational Training Institute (NVTI) for, Women, , • 15 Regional Vocational Training Institutes (RVTIs) for, Women, , • 12 Private Institute for Training of Trainers (IToTs), • 2 State Government IToTs, • Central Staff Training and Research Institute (CSTARI), • National Instructional Media Institute (NIMI), , DGT acts a secretariat and implementing arm of National, Council for Vocational Training (NCVT)., , 1, , Copyright Free Under CC BY Licence
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Familiar with the working of Industrial Training Institute system including stores, procedures, Objectives: At the end of this lesson you shall be able to, • to familarise with working of ITI, • identify the staff structure of the institute, • identify the available trades in the institute and their function, • brief about the stores procedure., The industrial training institute throughout India follow the, same syllabus pattern given by the National council for, Vocational Training (NCVT). In India there are about 13,350, Goverment ITIs and Private ITI 's Based on the Govt. of, India, Ministry of Skill Development and Entreprenurship, (MSDE) Annual report of 2016-2017. The Government, Industrial Training Institute in each state work under the, Directorate of Employment and Training which is a, department under the Labour Ministry in most of the, states., , 2, , The head of the industrial training institute is the Principal,, under whom there is one vice-principal, Group Instructor(s), Training officers and a number of Vocational Instructor(s), Assitant Training Officer(s) and Junior Training Officer and, so on as shown in the Organisation Chart of ITI. (Fig 1), In every industrial training institute there is a store and the, in charge of the store is storekeeper for inward and outward, movement of tools, equipment and consumable. The, instructor will indent the training requirement on receiving, from stores, the instructor will issue the training requirement, to the trainees according to the graded exercises as per, syllabus., , P & M : Fitter - Related Theory for Exercise 1.1.01, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.02, , Importance of safety and general precautions observed in the industry/shop, floor, Objectives: At the end of this lesson you shall be able to, • state the importance of safety, • list out the safety precautions to be observed in a industry/shop floor, • list out the personal safety precautions to be observed in machine shop, • list out the safety precautions to be observed while working on the machines., Generally accidents do not happen; they are caused. Most, accidents are avoidable. A good craftsman, having a, knowledge of various safety precautions, can avoid, accidents to himself and to his fellow workers and protect, the equipment from any damage. To achieve this, it is, essential that every person should follow safety procedure., (Fig 1), , Use the correct tools for the job., Keep the tools at their proper place., Wipe out split oil immediately., Replace worn out or damaged tools immediately., Never direct compressed air at yourself or at your, co-worker., Ensure adequate light in the workshop., Clean the machine only when it is not in motion., Sweep away the metal cuttings., Know everything about the machine before you start it., Personal safety, Wear a one piece overall or boiler suit., Keep the overall buttons fastened., Don't use ties and scarves., Roll up the sleeves tightly above the elbow., Wear safety shoes or boots, Cut the hair short., Don't wear a ring, watch or chain., Never lean on the machine., Don't clean hands in the coolant fluid., Don't remove guards when the machine is in motion., , Safety in a workshop can be broadly classified into 3, categories., , Don't use cracked or chipped tools., , •, , General safety, , − the workpiece is securely mounted, , •, , Personal safety, , − the feed machinery is in the neutral, , •, , Machine safety, , − the work area is clear., , General safety, , Don't start the machine until, , Keep the floor and gangways clean and clear., , Don't adjust clamps or holding devices while the machine, is in motion., , Move with care in the workshop, do not run., , Never touch the electrical equipment with wet hands., , Don't leave the machine which is in motion., , Don't use any faulty electrical equipment., , Don't touch or handle any equipment/ machine unless, authorised to do so., , Ensure that electrical connections are made by an, authorised electrician only., , Don't walk under suspended loads., , Concentrate on your work.Have a calm attitude., , Don't cut practical jokes while on work., 3, , Copyright Free Under CC BY Licence
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Do things in a methodical way., Don't engage yourself in conversation with others while, concentrating on your job., , Do not adjust tool or the workpiece unless the power is, off., Stop the machine before changing the speed., , Don't distract the attention of others., , Disengage the automatic feeds before switching off., , Don't try to stop a running machine with hands., , Check the oil level before starting the machine., , Machine safety, , Never start a machine unless all the safety guards are in, position., , Switch off the machine immediately if something goes, wrong., Keep the machine clean., Replace any worn out or damaged accessories, holding, devices, nuts, bolts etc as soon as possible., , Take measurements only after stopping the machine., Use wooden planks over the bed while loading and, unloading heavy jobs., Safety is a concept, understand it. Safety is a, habit, cultivate it., , Do not attempt operating the machine until you know how, to operate it properly., , Approach on soft skills, Objectives : At the end of this lesson you shall be to, • state the concept of soft skill, • list the important common soft skills, • brief the employability aspect of training, • brief the further learning scope., Concept, Soft skills - refer to the cluster of personality traits, social, graces, facility with language, personal habits, friendliness,, and optimism that mark people to varying degrees. The, same can also be defined as-ability to interact, communicate positively & productively with others., Sometimes called “character skills”., More and more business are considering soft skills as, important job criteria. Soft skills are used in personal and, professional life. Hard skills/technical skills do not matter, without soft skills., Common Soft Skills, , Job area completion of training: This highlights the, employability aspect on completion of training. The trainee, should be aware of various prospects available in present, market scenario along with scope for self-employment., For example a trainee with NTC engineering trade may, opt for:, Various job available in different industries in, India and Abroad., After successfull completion of ITI training in any one of, the engineering trade one can see appointment in, engineering workshop/Factories (Public Sector, Private, Sector and Government Industries) in India and Abroad as, technician/Skilled worker., , •, , Strong work ethic, , •, , Positive attitude, , •, , Good communication skills, , One can start is own factory/ancillary unit or design, products manufacture and became an entrepreneur., , •, , Interpersonal skills, , Further learning scope, , •, , Time management abilities, , •, , Apprentice training in designated trade., , •, , Problem-solving skills, , •, , Craft Instructor certificate course., , •, , Team work, , •, , Diploma in relevant Engineering., , •, , Initiative, Motivation, , •, , Self-confidence, , •, , Loyalty, , •, , Ability to accept and learn from criticism, , •, , Flexibility, Adaptability, , •, , Working well under pressure, , 4, , Self employment, , P & M : Fitter - Related Theory for Exercise 1.1.02, , Copyright Free Under CC BY Licence
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Personal Protective Equipment (PPE), Objectives: At the end of this lesson you shall be able to, • state what is personal protective equipment and its purpose, • name the two categories of personal protective equipment, • list the most common type of personal protective equipment, • list the conditions for selection of personal protective equipment., Personal Protective Equipment (PPE), Devices, equipments, or clothing used or worn by the, employees, as a last resort, to protect aginst hazards in, the workplace. The primary approach in any safety effort, is that the hazard to the workmen should be eliminated, or the workmen through the use of personal protective, controlled by engineering methods rather than protecting, the workmen through the use of personal protective, equipment (PPE). Engineering methods could include, design change, substitution ventilation, mechanical, handling, automation, etc. in situations where it is not, possible to introduce any effective engineering methods, for controlling hazards, the workman shall use appropriate, types of PPE., As changing times have modernized the workplace,, government and advocacy groups have brought more safety, standards to all sorts of work environments.The Factories, Act, 1948 and several other labour legislations 1996 have, provisions for effective use of appropriate types of PPE., Use of PPE is very important., Ways to ensure workplace safety and use personal, protective equipment (PPE) effectively., •, , •, , •, , •, , Workers to get up-to date safety information from the, regulatory agencies that oversees workplace safety in, their specific area., To use all available text resources that may be in work, area and for applicable safety information on how to, use PPE best., When it comes to the most common types of personal, protective equipment, like goggles, gloves or bodysuits,, these items are much less effective if they are not worn, at all times, or whenever a specific danger exists in a, work process. Using PPE consistently will help to avoid, some common kinds of industrial accidents., , •, , Inspection of gear throughly to make sure that it has, the standard of quality and adequately protect the user, should be continuously carried out., , Categories of PPE-Small's', Depending upon the nature of hazard, the PPE is broadly, divided into the following two categories., Non- respiratory : Those used for protection against injury, from outside the body, i.e. for protecting the head,eye,, face, hand, arm, foot, leg and other body parts, Respiratory: Those used for protection from harm due to, inhalation of contaminated air., They are to meet the applicable BIS (Bureau of Indian, Standards) standards for different types of PPE., The guidelines on 'Personal Protective Equipment' is, issued to facilitate the plant management in maintaining, an effective programme with respect to protection of, persons against hazards, which cannot be eliminated or, controlled by engineering methods listed in table 1., Table 1, No, , Title, , PPE1, , Helmet, , PPE2, , Safety footwear, , PPE3, , Respiratory protective equipment, , PPE4, , Arms and hands protection, , PPE5, , Eyes and face protection, , PPE6, , Protective clothing and coverall, , PPE7, , Ears protection, , PPE8, , Safety belt harness, , Personal protective gear is not always enough to protect workers against workplace dangers, Knowing more, about the overall context of your activity can help to, fully protect from anything that might threaten health, and safety on the job., , P & M : Fitter - Related Theory for Exercise 1.1.02, , Copyright Free Under CC BY Licence, , 5
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Personal protective equipments and their uses and hazards are listed in Table 2, Types of protection, , Hazards, , PPE to be used, , Head protection (Fig 1), , 1. Falling objects, 2. Striking against objects, 3. Spatter, , Helmets, , Foot protection (Fig 2), , 1. Hot spatter, 2. Falling objects, 3. Working wet area, , Leather leg guards, Safety shoes, Gum boots, , Nose (Fig 3), , 1. Dust particles, 2. Fumes/gases/ vapours, , Nose mask, , 1. Heat burn due to direct contact, 2. Blows spark moderate heat, 3. Electric shock, , Hand gloves, , Hand Protecion (Fig 4), , 6, , P & M : Fitter - Related Theory for Exercise 1.1.02, , Copyright Free Under CC BY Licence
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Types of protection, , Hazards, , PPE to be used, , Eye protection (Fig 5 & Fig6), , 1. Flying dust particles, 2. UV rays, IR rays heat and, High amount of visible, , Goggles, Face shield, radiation, Hand shield, Head shield, , Face protection (Fig 6 &Fig 7), , 1. Spark generated during, Welding, grinding, 2. Welding spatter striking, 3. Face protection from, UV rays, , Face shield, Head shield with or, without ear muff, Helmets with welders, Screen for welders, , 1. High noise level, , Ear plug, Ear muff, , Ear protection (Fig 7), , Ear muffs, , Ear plug, , P & M : Fitter - Related Theory for Exercise 1.1.02, , Copyright Free Under CC BY Licence, , 7
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Types of protection, , Hazards, , Body protection (Fig 8, & Fig 9), , PPE to be used, , 1. Hot particles, , Leather aprons, , Quality of PPE's, , Proper use of PPEs, , PPE must meet the following criteria with regard to its, quality-provide absolute full pretection against possible, hazard and PPE's be so designed and manufactured out, of materials that it can withstand the hazards against, which it is intended to be used., , Having selected the proper type of PPE, it is essential that, the workman wears it. Often the workman avoids using, PPE. The following factors influence the solution to this, problem., •, , The extent to which the workman understands the, necessity of using PPE, , Selection of PPE's requires certain conditions, •, , Nature and severity of the hazard, , •, , •, , Type of contaminant, its concentration and loacation, of contaminated area with respect to the source of, respirable air, , The ease and comfort with which PPE can be worn, with least interference in normal work procedures, , •, , The available economic, social and disciplinary, sanctions which can be used to influence the attitude, of the workman, , •, , The best solution to this problem is to make wearing of, PPE' mandatory for every employee., , •, , In other places, education and supervision need to be, intensified. When a group of workmen are issued PPE, for the first time., , •, , Expected activity of workman and duration of work,, comfort of workman when using PPE, , •, , Operating characteristics and limitation of PPE, , •, , Easy of maintenance and cleaning, , •, , Conformity to Indian / International standards and, availability of test certificate., , 8, , P & M : Fitter - Related Theory for Exercise 1.1.02, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.03, , First-aid, Objectives: At the end of this lesson you shall be able to, • state what is first aid, • list the key aims of first aid, • explain the ABC of the first aid, • brief how to give first-aid for a victim who need first aid., First aid is defined as the immediate care and support, given to an acutely injured or ill person, primarily to save, life, prevent further deterioration or injury, plan to shift the, victims to safer places, provide best possible comfort and, finally help them to reach the medical centre/ hospital, through all available means. It is an immediate life-saving, procedure using all resources available within reach., Imparting knowledge and skill through institutional teaching, at younger age group in schools, colleges, entry point at, industry level is now given much importance. Inculcating, such habits at early age, helps to build good healthcare, habits among people., First aid procedure often consists of simple and basic life, saving techniques that an individual performs with proper, training and knowledge., The key aims of first aid can be summarized in three key, points:, •, , •, , •, , Preserve life: If the patient was breathing, a first aider, would normally place them in the recovery position,, with the patient leant over on their side, which also has, the effect of clearing the tongue from the pharynx. It, also avoids a common cause of death in unconscious, patients, which is choking on regurgitated stomach, contents. The airway can also become blocked through, a foreign object becoming lodged in the pharynx or, larynx, commonly called choking. The first aider will, be taught to deal with this through a combination of, 'back slaps' and 'abdominal thrusts'. Once the airway, has been opened, the first aider would assess to see if, the patient is breathing., Prevent further harm: Also sometimes called prevent, the condition from worsening, or danger of further injury,, this covers both external factors, such as moving a, patient away from any cause of harm, and applying, first aid techniques to prevent worsening of the condition,, such as applying pressure to stop a bleed becoming, dangerous., Promote recovery: First aid also involves trying to, start the recovery process from the illness or injury,, and in some cases might involve completing a, treatment, such as in the case of applying a plaster to, a small wound., , Training, Basic principles, such as knowing to use an adhesive, bandage or applying direct pressure on a bleed, are often, acquired passively through life experiences. However, to, , provide effective, life-saving first aid interventions requires, instruction and practical training. This is especially true, where it relates to potentially fatal illnesses and injuries,, such as those that require cardiopulmonary resuscitation, (CPR); these procedures may be invasive, and carry a, risk of further injury to the patient and the provider. As, with any training, it is more useful if it occurs before an, actual emergency, and in many countries, emergency, ambulance dispatchers may give basic first aid, instructions over the phone while the ambulance is on the, way. Training is generally provided by attending a course,, typically leading to certification. Due to regular changes, in procedures and protocols, based on updated clinical, knowledge, and to maintain skill, attendance at regular, refresher courses or re-certification is often necessary., First aid training is often available through community, organization such as the Red cross and St. John, ambulance., ABC of first aid, ABC stands for airway, breathing and circulation., •, , Airway: Attention must first be brought to the airway, to ensure it is clear. Obstruction (choking) is a lifethreatening emergency., , •, , Breathing: Breathing if stops, the victim may die soon., Hence means of providing support for breathing is an, important next steps. There are several methods, practiced in first aid., , •, , Circulation: Blood circulation is vital to keep person, alive. The first aiders now trained to go straight to chest, compressions through CPR methods., , When providing first aid one needs to follow some rule., There are certain basic norms in teaching and training, students in the approach and administration of first aid to, sick and injured., Not to get panic, Panic is one emotion that can make the situation more, worse. People often make mistake because they get, panic. Panic clouds thinking and causes mistakes. First, aider need calm and collective approach. If the first aider, himself is in a state of fear and panic gross mistakes, may result. It's far easier to help the suffering, when they, know what they are doing, even if unprepared to encounter, a situation. Emotional approach and response always lead, to wrong doing and may cloud one to do wrong procedures., Hence be calm and focus on the given institution. Quick, and confident approach can lessen the effect of injury., 9, , Copyright Free Under CC BY Licence
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Call medical emergencies, , Cleaning and dressing, , If the situation demands, quickly call for medical, assistance. Prompt approach may save the life., , Always clean the wound thoroughly before applying the, bandage lightly wash the wound with clean water., , Surroundings play vital role, , Not to use local medications on cuts or open wounds, , Different surroundings require different approach. Hence, first aider should study the surrounding carefully. In other, words, one need to make sure that they are safe and are, not in any danger as it would be of no help that the first, aider himself get injured., , They are more irritating to tissue than it is helpful. Simple, dry cleaning or with water and some kind of bandage are, best., , Do no harm, Most often over enthusiastically practiced first aid viz., administering water when the victim is unconscious, wiping, clotted blood (which acts as plug to reduce bleeding),, correcting fractures, mishandling injured parts etc., would, leads to more complication. Patients often die due to wrong, FIRST AID methods, who may otherwise easily survive., Do not move the injured person unless the situation, demands. It is best to make him lie wherever he is because, if the patient has back, head or neck injury, moving him, would causes more harm., This does not mean do nothing. It means to make sure, that to do something the care givers feel confident through, training would make matters safe. If the first aider is not, confident of correct handling it is better not to intervene of, do it. Hence moving a trauma victim, especially an, unconscious one, need very careful assessment. Removals, of an embedded objects (Like a knife, nail) from the wound, may precipitate more harm (e.g. increased bleeding)., Always it is better to call for help., Reassurance, Reassure the victim by speaking encouragingly with him., Stop the bleeding, If the victim is bleeding, try to stop the bleeding by applying, pressure over the injured part., Golden hours, India have best of technology made available in hospitals, to treat devastating medical problem viz. head injury,, multiple trauma, heart attack, strokes etc, but patients, often do poorly because they don't gain access to that, technology in time. The risk of dying from these conditions,, is greatest in the first 30 minutes, often instantly. This, period is referred to as Golden period. By the time the, patient reach hospitals, they would have passed that, critical period. First aid care come handy to save lives. It, helps to get to the nearest emergency room as quickly as, possible through safe handling and transportation. The, shorter that time, the more likely the best treatment, applied., Maintain the hygiene, Most importantly, first aider need to wash hands and dry, before giving and first aid treatment to the patient or wear, gloves in order to prevent infection., , CPR (Cardio-Pulmonary Resuscitation) can be lifesustaining, CPR can be life sustaining. If one is trained in CPR and, the person is suffering from choking or finds difficulty in, breathing, immediately begin CPR. However, if one is not, trained in CPR, do not attempt as you can cause further, injury. Bur some people do it wrong. This is a difficult, procedure to do in a crowded area. Also there are many, studies to suggest that no survival advantage when, bystanders deliver breaths to victims compared to when, they only do chest compressions. Second, it is very difficult, to carry right maneuver in wrong places. But CPR, if, carefully done by highly skilled first aiders is a bridge that, keeps vital organs oxygenated until medical team arrives., Declaring death, It is not correct to declare the victim's death at the accident, site. It has to be done by qualified medical doctors., How to report an emergency?, Reporting an emergency is one of those things that seems, simple enough, until actually when put to use in emergency, situations. A sense of shock prevail at the accident sites., Large crowd gather around only with inquisitive nature,, but not to extend helping hands to the victims. This is, common in road side injuries. No passerby would like to, get involved to assist the victims. Hence first aid, management is often very difficult to attend to the injured, persons. The first aiders need to adapt multitask strategy, to control the crowd around, communicate to the rescue, team, call ambulance etc., all to be done simultaneously., The mobile phones helps to a greater deal for such, emergencies. Few guidelines are given below to approach, the problems., Assess the urgency of the situation. Before you report an, emergency, make sure the situation is genuinely urgent., Call for emergency services if you believe that a situation, is life-threatening or otherwise extremely distruptive., , • A crime, especially one that is currently in progress. If, you're reporting a crime, give a physical description of, the person committing the crime., , • A fire - If you're reporting a fire, describe how the fire, stated and where exactly it is located. If someone has, already been injured or is missing, report that as well., , • A life-threatening medical emergency, explain how the, incident occurred and what sysmptoms the person, currently displays., , • A car crash - Location, serious nature of injures, vehicle's, details and registration, number of people involved etc., 10, , P & M : Fitter - Related Theory for Exercise 1.1.03, , Copyright Free Under CC BY Licence
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Call emergency service, , Determine responsiveness, , The emergency number varies - 100 for Police & Fire. 108, for Ambulance., , If a person is unconscious, try to rouse them by gently, shaking and speaking to them., , Report your location, The first thing the emergency dispatcher will ask is where, you are located, so the emergency services can get there, as quickly as possible. Give the exact street address, if, you're not sure of the exact address, give approximate, information., , If the person remains unresponsive, carefully, roll them on the side (recovery position) and, open his airway., •, , Keep head and neck aligned., , •, , Carefully roll them onto their back while holding his, head., , •, , Open the airway by lifting the chin. (Fig 1), , Give the dispatcher your phone number, This information is also imperative for the dispatcher to, have, so that he or she is able to call back if necessary., Describe the nature of the emergency, Speak in a calm, clear voice and tell the dispatcher why, you are calling. Give the most important details first, then, answer the dispatcher's follow-up question as best as you, can., Do not hang up the phone until you are instructed to do, so. Then follow the instructions you were given., Basic first aid, Basic first aid refers to the initial process of assessing, and addressing the needs of someone who has been injured, or is in physiological distress due to choking, a heart, attack, allergic reactions, drugs or other medical, emergencies. Basic first aid allows one to quickly, determine a person's physical condition and the correct, course of treatment., , Look, listen and feel for signs of breathing, Look for the victim's chest to raise and fall, listen for sounds, of breathing., If the victim is not breathing, see the section below, •, , Important guideline for first aiders, Evaluate the situation, , If the victim is breathing, but unconscious, roll them, onto their side, keeping the head and neck aligned with, the body. This will help drain the mouth and prevent the, tongue or vomit from blocking the airway., , Check the victim's circulation, , Are there things that might put the first aider at risk. When, faced with accidents like fire, toxic smoke, gasses, an, unstable building, live electrical wires or other dangerous, scenario, the first aider should be very careful not to rush, into a situation, which may prove to be fatal., , Look at the victim's colour and check their pulse (the, carotid artery is a good option; it is located on either side, of the neck, below the jaw bone). If the victim does not, have a pulse, start CPR., Treat bleeding, shock and other problems as needed, , Remember A-B-Cs, , •, , Airway - Does the person have an unobstructed airway?, , After establishing that the victim is breathing and has a, pulse, next priority should be to control any bleeding., Particularly in the case of trauma, preventing shock is the, priority., , •, , Breathing - Is the person breathing?, , •, , •, , Circulation - Does the person show a pulse at major, pulse points (wrist, carotid artery, groin), , Stop bleeding: Control of bleeding is one of the most, important things to save a trauma victim. Use direct, pressure on a wound before trying any other method of, managing bleeding., , •, , Treat shock: Shock, a loss of blood flow from the body,, frequently follows physical and occasionally, psychological trauma. A person in shock will frequently, have ice cold skin, be agitated or have an altered mental, status, and have pale colour to the skin around the, face and lips. Untreated, shock can be fatal. Anyone, who has suffered a severe injury or life-threatening, situation is at risk for shock., , The ABCs of first aid refer to the three critical things the, first aiders need to look for., , Avoid moving the victim, Avoid moving the victim unless they are in immediate, danger. Moving a victim will often make injuries worse,, especially in the case of spinal cord injuries., Call emergency services, Call for help or tell someone else to call for help as soon, as possible. If alone in at the accident scene, try to, establish breathing before calling for help, and do not leave, the victim alone unattended., , P & M : Fitter - Related Theory for Exercise 1.1.03, , Copyright Free Under CC BY Licence, , 11
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•, , Choking victim: Choking can cause death or, permanent brain damage within minutes., , •, , Treat a burn: Treat first and second degree burns by, immersing or flushing with cool water. Don't use creams,, butter or other ointments, and do not pop blisters. Third, degree burns should be covered with a damp cloth., Remove clothing and jewellery from the burn, but do, not try to remove charred clothing that is stuck to burns., , •, , •, , Treat a concussion: If the victim has suffered a blow, to the head, look for signs of concussion. Common, symptoms are: loss of consciousness following the, injury, disorientation or memory impairment, vertigo,, nausea, and lethargy., Treat a spinal injury victim: If a spinal injury is, suspected, it is especially critical, not move the victim's, head, neck or back unless they are in immediate, danger., , •, , Headache, , •, , Inability to speak or move parts of his or her body (see, stroke symptoms), , •, , Light headedness, , •, , Loss of bowel or bladder control (incontinence), , •, , Rapid heartbeat (palpitation), , •, , Stupor, , First aid, •, , Call EMERGENCY number., , •, , Check the person's airway, breathing, and pulse, frequently. If necessary, begin rescue breathing and, CPR., , •, , If the person is breathing and lying on the back and, after ruling out spinal injury, carefully roll the person, onto the side, preferably left side. Bend the top leg so, both hip and knee are at right angles. Gently tilt the, head back to keep the airway open. If breathing or pulse, stops at any time, roll the person on to his back and, begin CPR., , •, , If there is a spinal injury, the victims position may have, to be carefully assessed. If the person vomits, roll the, entire body at one time to the side. Support the neck, and back to keep the head and body in the same, position while you roll., , •, , Keep the person warm until medical help arrives., , •, , If you see a person fainting, try to prevent a fall. Lay, the person flat on the floor and raise the level of feet, above and support., , •, , If fainting is likely due to low blood sugar, give the person, something sweet to eat or drink when they become, conscious., , Stay with the victim until help arrives, Try to be a calming presence for the victim until assistance, can arrive., Unconsciousness (COMA), Unconscious also referred as Coma, is a serious life, threatening condition, when a person lie totally senseless, and do not respond to calls, external stimulus. But the, basic heart, breathing, blood circulation may be still intact,, or they may also be failing. If unattended it may lead to, death., The condition arises due to interruption of normal brain, activity. The causes are too many., •, , Shock (Cardiogenic, Neurogenic), , •, , Head injury (Concussion, Compression), , •, , Asphyxia (obstruction to air passage), , •, , Extreme of body temperature (Heat, Cold), , DO NOT, , •, , Cardiac arrest (Heart attack), , •, , Do not give an unconscious person any food or drink., , •, , Stroke (Cerebro-vascular accident), , •, , Do not leave the person alone., , •, , Blood loss (Haemorrhage), , •, , •, , Dehydration (Diarrohea & vomiting), , Do not place a pillow under the head of an unconscious, person., , •, , Diabetes (Low or high sugar), , •, , Do not slap an unconscious person's face or splash, water on the face to try to revive him., , •, , Blood pressure (Very low or very high), , •, , Over dose of alcohol, drugs, , •, , Poisoning (Gas, Pesticides, Bites), , •, , Epileptic fits (Fits), , •, , Hysteria (Emotional, Psychological), , The following symptoms may occur after a person has, been unconscious:, •, , Confusion, , •, , Drowsiness, , 12, , Loss of consciousness may threaten life if the, person is on his back and the tongue has, dropped to the back of the throat, blocking the, airway. Make certain that the person is, breathing before looking for the cause of, unconsciousness. If the injuries permit, place, the casualty in the recovery position with the, neck extended. Never give anything by mouth, to an unconscious casualty., , P & M : Fitter - Related Theory for Exercise 1.1.03, , Copyright Free Under CC BY Licence
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Shock (Fig 3), A severe loss of body fluid will lead to a drop in blood, pressure. Eventually the blood's circulation will deteriorate, and the remaining blood flow will be directed to the vital, organs such as the brain. Blood will therefore be directed, away from the outer area of the body, so the victim will, appear pale and the skin will feel ice cold., , How to diagnose an unconscious injured person, •, , Consider alcohol: look for signs of drinking, like empty, bottles or the smell of alcohol., , •, , Consider epilepsy: are there signs of a violent seizure,, such as saliva around the mouth or a generally, dishevelled scene?, , •, , Think insulin: might the person be suffering from, insulin shock (see 'How to diagnose and treat insulin, shock")?, , •, , Think about drugs: was there an overdose? Or might, the person have under dosed - that is not taken enough, of a prescribed medication?, , •, , Consider trauma: is the person physically injured?, , •, , Look for signs of infection: redness and/ or red streaks, around a wound., , •, , Look around for signs of Poison: an empty bottle of, pills or a snakebite wound., , •, , Consider the possibility of psychological trauma:, might the person have a psychological disorder of some, sort?, , •, , Consider stroke, particularly for elderly people., , •, , Treat according to what you diagnose., , P & M : Fitter - Related Theory for Exercise 1.1.03, , Copyright Free Under CC BY Licence, , 13
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.04, , Guidelines for good shop floor maintenance, Objectives: At the end of this lesson you shall be able to, • list the benefits of a shop floor maintenance, • state what is 5s, • list the benefits of 5s., Benefits of a shop floor maintenance, , 5S Wheel (Fig 1), , Some of the benefits which may be derived from the, utilization of a good Shop Floor Maintenance are as, follows:, , The Benefits of the 5s system, , •, , Improved productivity, , •, , Improved operator efficiencies., , •, , Improved support operations such as replenishment, moves and transportation of work in process and, finished goods., , •, , Reduction of scrap, , •, , Better control of your manufacturing process, , •, , More timely information to assist shop floor, supervisors in managing their assigned production, responsiblities., , •, , Reduction of down time due to better machine and, tool monitoring., , •, , Better control of work in progress inventory, what is, and where it is improved on time schedule, performance., , •, , Increases in producitivity, , •, , Increases in quality, , •, , Reduction in cost, , 5S concept, 5S is a japanese methodology for works place, organisation. In japanese it stands for seiri (SORT),, seiton (SET), seiso (SHINE), seiketsu (STANDARDIZE) and shitsuke (SUSTAIN)., The list describes how to organize a work space for, effciency and effectiveness by identifying and storing, the items used, maintaining the area and items, and, sustaining the new order. The list describes how to organize a work space for effciency and effectiveness by, identifying and storing the items used. maintaining the, area and items, and sustaining the new order., , 14, , Copyright Free Under CC BY Licence
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Importance of housekeeping, Objectives: At the end of this lesson you shall be able to, • list the steps involves in house keeping, • state good shop floor practices followed in industry, Housekeeping, , •, , The following activities to be performed for better up keep, of working environment:, , All workers are communicated with daily target on, manufacturing, activities., , •, , 1 Cleaning of shop floor: Keep clean and free from, accumulation of dirt and scrap daily, , Informative charts are used to post production, quality, and safety results compared to achievements., , •, , 2 Cleaning of Machines : Reduce accidents to keep, machines cleaned well, , Workers are trained on written product quality standards., , •, , 3 Prevention of Leakage and spillage: Use splash, guards in machines and collecting tray, , Manufactured parts are inspected to ensure adherence, to quality standards., , •, , 4 Disposal of Scrap- Empty scrap, wastage, swarf from, respective containers regularly, , Production processes are planned by engineering to, minimize product variation., , •, , 5 Tools Storage- Use special racks, holders for respective tools, , 5s methods are used to organize the shop floor and, production lines., , •, , Workers are trained on plant safety practices in accordance with Occupational Safety Health (OSH) standards., , •, , Workers are trained on "root cause" analysis for determining the causes of not following., , •, , A written preventive maintenance plan for upkeep of, plant,machinery & equipment, , •, , Management meets with plant employees regularly to, get input on process improvements., , •, , Process Improvement Teams are employed to implement "best practices", , 6 Storage Spaces: Identify storage areas for respective, items. Do not leave any material in gangway, 7 Piling Methods- Do not overload platform, floor and, keep material at safe height., 8 Material handling: Use forklifts, converyors and hoist, according to the volume and weight of the package., Good shop floor practices followed in industry, Good Shop floor practices are motivating action plans for, improvement of the manufacturing process., , Disposal of waste material, Objectives: At the end of this lesson you shall be able to, • state what is waste material, • list the waste materials in a work shop, • explain the methods of disposal of waste material., • state advantage of disposal of waste material., • state colour code for bins for waste segregation., Waste material, , List of waste material (Fig 1), , industrial waste is the waste produced by industrial activity, such as that of factories, mills and mines., , •, , Cotton waste, , •, , Metal chips of different material., , •, , Oily waste such as lubricating oil, coolant etc., , •, , Other waste such electrical, glass etc., , P & M : Fitter - Related Theory for Exercise 1.1.04, , Copyright Free Under CC BY Licence, , 15
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Methods of waste disposal, , Incineration (Fig.3), It is the process of controlled combustion of garbage to, reduce it to incombustible matter, ash, waste gas and, heat. It is treated and released into the environment (Fig.3)., This reduced 90% volume of waste, some time the heat, generated used to produce electric power., , Recycling, Recyling is one of the most well known method of managing, waste. It is not expensive and can be easily done by you., If you carry out recycling. you will save a lot of energy,, resources and thereby reduce pollution., Waste compaction, , Composting, This is a natural process that is completely free of any, hazardous by-products. This process involves breaking, down the materials into organic compounds that can be, used as manure., Landfills, Waste management through the use of landfills involves, the use of a large area. This place is dug open and filled with, the waste., Burning the waste material, If you cannot recycle or if there are no proper places for, setting up landfills, you can burn the waste matter generated, in your household. Controlled burning of waste at high, temperatures to produce steam and ash is a preferred, waste disposal techinque., Advantage of waste disposal:, •, , Ensures workshop neat & tidy, , •, , Reduces adverse impact on health, , •, , Improves economic effciency, , •, , Reduce adverse impact on environment, , 16, , The waste materials such as cans and plastic bottles compact into blocks and send for recycling. This process space, need, thus making transportation and positioning easy., Colour code for bins for waste segregation given in, Table-1, Table-1, Sl.No., , Waste Material, , Color code, , 1, , Paper, , Blue, , 2, , Plastic, , Yellow, , 3, , Metal, , Red, , 4, , Glass, , Green, , 5, , Food, , Black, , 6, , Others, , Sky blue, , P & M : Fitter - Related Theory for Exercise 1.1.04, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.05, , Occupational health and safety, Objectives: At the end of this lesson you shall be able to, • define safety, • state the goal of occupational health and safety, • explain need of occupational health and safety, • state the occupational hygiene, • explain occupational hazards, • brief the occupational disease., Safety, , •, , Safety means freedom or protection from harm, danger,, hazard, risk, accident, injury or damage., Occupational health and safety, •, , Occupational health and safety is concerned with, protecting the safety, health and welfare of people, engaged in work or employment., , •, , The goal is to provide a safe work environment and to, prevent hazards., , •, , It may also protect co-workers, family members,, employers, customers, suppliers, neaby communities,, and other members of the public who are affected by, the workplace environment., , •, , it involves interactions among many related areas,, including occupational medicine, occupational (or, industrial) hygiene, public health, and safety, engineering, chemistry, and health physics., , Need of occupational health and safety, •, , Health and safety of the employees is an important, aspect of a company's smooth and successful, functioning., , Which may cause sickness, impaired health and well, being (or) significant discomfort and inefficiency among, workers., , Anticipation (Identification): Methods of identification, of possible hazards and their effects on health., Recognition (Acceptance): Acceptance of ill-effects of, the identified hazards, Evaluation (Measurement & Assessment): Measuring, or calculating the hazard by Instruments, Air sampling, and Analysis, comparison with standards and taking, judgement whether measured or calculated hazard is more, or less than the permissible standard., Control of workplace hazards: Measures like, Engineering and Administrative controls, medical, examination use of Personal Protective Equipment (PPE), education, training and supervision., Occupational hazards, "Source or situation with a potenital for harm in terms of, injury or ill health, damage to property, damage to the, workplace environment, or a combination of these", Types of occupational health hazards, , It is a decisive factor in organizational effectiveness. It, ensures an accident-free industrial environment., , •, , Physical Hazards, , •, , Chemical Hazards, , •, , Proper attention to the safety and welfare of the, employees can yield valuable returns., , •, , Biological Hazards, , •, , Physiological Hazards, , •, , Improving employee morale, , •, , Psychological Hazards, , •, , Reducing absenteeism, , •, , Mechanical Hazards, , •, , Enhancing productivity, , •, , Electrical Hazards, , •, , Minimizing potential of work-related injuries and, illnesses, , •, , Ergonomic Hazards, , •, , Increasing the quality of manufactured products and /, rendered services., , •, , 1 Physical hazards, •, , Noise, , Occupational (Industrial) hygiene, , •, , Heat and cold stress, , •, , •, , Vibration, , •, , Radiation (ionising & Non-ionising ), , •, , Illumination etc.,, , •, , Occupational hygiene is anticipation, recognition,, evaluation and control of work place hazards (or), environmental factors (or) stresses, This is arising in (or) from the workplace., , 17, , Copyright Free Under CC BY Licence
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2 Chemical hazards, , •, , Accident proneness etc,, , •, , Inflammable, , •, , Emotional disturbances, , •, , Explosive, , -, , violence, , •, , Toxic, , -, , bullying, , •, , Corrosive, , -, , sexual harassment, , •, , Radioactive, , 6 Mechanical, , 3 Biological hazards, , •, , Unguarded machinery, , •, , Bacteria, , •, , No fencing, , •, , Virus, , •, , No safety device, , •, , Fungi, , •, , No control device etc.,, , •, , Plant pest, , 7 Electrical, , •, , Infection, , •, , No earthing, , 4 Physiological, , •, , Short circuit, , •, , Old age, , •, , Current leakage, , •, , Sex, , •, , Open wire, , •, , lll health, , •, , No fuse or cut off device etc,, , •, , Sickness, , 8 Ergonomic, , •, , Fatigue., , •, , Poor manual handling technique, , 5 Psychological, , •, , Wrong layout of machinery, , •, , Wrong attitude, , •, , Wrong design, , •, , Smoking, , •, , Poor housekeeping, , •, , Alocholism, , •, , Awkward position, , •, , Unskilled, , •, , Wrong tools etc,, , •, , Poor discipline, , 18, , Safety Slogan, , -, , absentism, , -, , disobedience, , -, , aggressive behaviour, , A safety rule breaker, is an accident maker, , P & M : Fitter - Related Theory for Exercise 1.1.05, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.06, , Safety Sign, Objectives: At the end of this lesson you shall be able to, • list three kinds of road sign, • describe the marking on the road, • describe the various police traffic hand signal and light signal, • list the collision causes., In older days road locomotive carrying a red flag by day and, red lantern by night. Safety is the prime motive of every, traffic., Kinds of road signs, Mandatory, Cautionary and, Informatory, Mandatory sign (Fig 1), Violation of mandatory sign can lead to penalities. Ex., Stop, give way limits, prohibited, no parking and compulsory, sign., , Marking lines on road (Fig 4), •, , Marking lines are directing or warn to the moving, vehicles, cyclist and pedestrians to follow the law., , •, , Single and short broken lines with middle of the road, allow the vehicle to cross the dotted lines safely, overtake whenever required., , •, , When moving vehicle approaching pedestrian crossing,, be ready to slow down or stop to let people cross., , •, , Do not overtake in the vicinity of pedestrain crossing., , Cautionary signs (Fig 2), Cautionary/ warning signs are especially safe. Do's and, don'ts for pedestrians, cyclists, bus passengers and, motorists., Information signs (Fig 3), Information signs are especially benefit to the passengers, and two wheelers., , 19, , Copyright Free Under CC BY Licence
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Police signals, To stop a vehicle approaching from behind. Fig 5(1), To stop a vehicle coming from front. Fig 5(2), To stop vechicles approaching simultaneously from front, and behind. Fig 5(3), To stop traffic approaching from left and wanting to turn, right. Fig 5(4), To stop traffic approaching from the right to allow traffic, from left turn right. Fig 5(5), To allow traffic coming from the right and turning right by, stopping traffic approaching from the left. Fig 5(6), , Green means you may go on if the way is clear. Take, special care if you mean to turn left or right and give way, to pedestrians who are crossing. Fig 6(3), Amber means stop at the stop line. you may only go on if, the amber appears after you have crossed the stop line or, so close to it that to pull up may not be possible. Fig 6(4), Green arrow means that you may go in the direction shown, by the arrow. You may do this whatever other lights may, be showing. Fig 6(5), Pedestrians - do not cross. Fig 6(6), Pedestrians - cross now. Fig 6(7), , Warning signal closing all traffic. Fig 5(7), , Flashing red means stop at the stop line and if the way is, clear proceed with caution. Fig 6(8), , Beckoning on vehicles approaching from left. Fig 5(8), , Flashing amber means proceed with caution. Fig 6(9), , Collision causes, Beckoning on vehicles approaching from right. Fig 5(9), , Three factors are responsible for collision, , Beckoning on vehicles from front. Fig 5(10), , -, , Roads, , Traffic light signals, , -, , Vehicles and, , Red means stop. Wait behind the stop line on the carriage, way. Fig 6(1), , -, , Drivers., , Red and amber also means stop. Do not pass through or, start until green shows. Fig 6 (2), , 20, , The fig 7 shows approximately proportionate causes of, collision. In wrong attitudes such that avoid foolish acts at, the wheel. Driving time is not play time. (Fig 8), , P & M : Fitter - Related Theory for Exercise 1.1.06, , Copyright Free Under CC BY Licence
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Safety practice, Objectives : At the end of this lesson you shall be to, • state the responsibilities of employer and employees, • state the safety attitude and list the four basic categories of safety signs., Safety, The state of being safe, freedom from the occurrence or, risk of injury, danger or loss., Responsibilities, Safety doesn't just happen - it has to be organised and, achieved like the work-process of which it forms a part., The law states that both an employer and his employees, have a responsibility in this behalf., Employer's responsibilities, The effort a firm puts into planning and organising work,, training people, engaging skilled and competent workers,, maintaining plant and equipment, and checking, inspecting, and keeping records - all of this contributes to the safety, in the workplace., The employer will be responsible for the equipment, provided, the working coditions, what the employees are, asked to do, and the training given., Employee's responsibilities, You will be responible for the way you use the equipment,, how you do your job, the use you make of your training,, and your general attitude to safety., A great deal is done by employers and other people to, make your working life safer; but always remember you, are responsible for your own actions and the effect they, have on others. You must not take that responsibility lightly., , may be written down, but more often than not, are just the, way a firm does things - you will learn these from other, workers as you do your job. They may govern the issue, and use of tools, protective clothing and equipment,, reporting procedures, emergency drills, access to, restricted areas, and many other matters. Such rules are, essential and they contribute to the efficiency and safety, of the job., Safety signs, As you go about your work on a construction site you will, see a variety of signs and notices. Some of these will be, familiar to you - a 'no smoking' sign for example; others, you may not have seen before. It is up to you to learn what, they mean - and to take notice of them. They warn of the, possible danger, and must not be ignored., Safety signs fall into four separate categories. These can, be recognised by their shape and colour. Sometimes they, may be just a symbol; other signs may include letters or, figures and provide extra information such as the clearance, height of an obstacle or the safe working load of a crane., The four basic categories of signs are as follows:, •, , prohibition signs (Fig 1 & Fig 5), , •, , mandatory signs (Fig 2 & Fig 6), , •, , warning signs (Fig 3 & Fig 7), , •, , information signs (Fig 4), , Rules and procedure at work, What you must do, by law is often included in the various, rules and procedures laid down by your employer. They, , P & M : Fitter - Related Theory for Exercise 1.1.06, , Copyright Free Under CC BY Licence, , 21
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Prohibition signs, Fig 1, , SHAPE, , Circular., , COLOUR, , Red border, and cross bar., Black symbol, on white, background, , MEANING, , Shows it must, not be done., , Example, , No smoking, , SHAPE, , Circular., , COLOUR, , White symbol, on blue, background, , MEANING, , Shows what, must be done, , Example, , Wear hand, protection, , SHAPE, , Triangular, , COLOUR, , Yellow, background, with black, border and, symbol., , MEANING, , Warns of, hazard or, danger., , Example, , Caution, risk of, electric shock., , Prohibition signs, , Mandatory signs, , Mandatory signs, Fig 2, , Warning signs, Fig 3, , Information signs, SHAPE, Fig 4, , 22, , Warning signs, , Square of oblong., , COLOUR, , White symbols, on green, background., , MEANING, , Indicates or, gives, information of, safety, provision., , Example, , First aid point., , P & M : Fitter - Related Theory for Exercise 1.1.06, , Copyright Free Under CC BY Licence
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Question about your safety, Do you know the general safety rules that cover your place, of work?, Are you familiar with the safety laws that govern you, particular job?, Do you know how to do your work without causing danger, to yourself, your workmates and the general public?, Are the plant, machinery and tools that you use really, safe? Do you know how to use them safely and keep, them in a safe condition?, , Do you wear all the right protective clothing, and have you, been provided with all the necessary safety equipment?, Have you been given all the necessary safety informaton, about the materials used?, Have you been given training and instruction to enable, you to do your job safely?, Do you know who is responsible for safety at your place, of work?, Do you know who are the appointed 'Safety, Representatives'?, , Response to emergencies - Power failure, System failure & Fire, Objectives: At the end of this lesson you shall be able to, • state the reason of emergency power failure, • state the cause of system failure, • state the fire safety and immediate actions., 1 If there is a power failure, start the emergency generator. This provides power to close the shutter, which is, the first priority. The generator will also keep the UPSs, and the cryogenic compressors running,, -, , Get a flash light., , -, , Look out for power transfer switch and switch over, to normal power to emergency power by pressing, the latch., , -, , Check the fuel valves open or not - Open the valves., , -, , Check to see that the main breaker switch ON the, generator is in OFF position., , -, , Move the starter switch of the generator to run position. The engine will start at once., , -, , Allow few minutes to warm up the engine., , -, , Check all the gauges, pressure, temperature, voltage and frequency., , -, , Check the "AC line" and "Ready" green light on the, front panel., , 2 System failure, -, , If the bug or virus, invades the system. The system, failure happens., , -, , Several varieties of bugs are there, , 1. Assasin bug, 2. Lightening bug, 3. Brain bug, For more details refer instruction manual for "System, failure"., 3 Fire failure, When fire alarm sounds in your buildings, 1. Evacuate to outside immediately., 2. Never go back, 3. Make way for fire fighters and their trucks to come, 4. Never use an elevator, 5. Do not panic, , Reporting emergency, Objectives : At the end of this lesson you shall be able to, • explain the report an emergency, • report through emergency services., Report an emergency, Reporting an emerency is one of those things that seems, simple enough, until actually when put to use in emergency situations. A sense of shock prevail at the accident, sites.Large crowd gather around only with inquisitive nature, but not to extend helping hands to the victims. This, is common in road side injuries. No passer by would like, to get involved to assist the victims. Hence first aid managements is often very difficult to attend to the injured persons. The first aiders need to adapt multitask strategy to, control the crowd around, communicate to the rescue, , team, call ambulance etc, all to be done simultaneously., The mobile phones helps to a greater deal for such emergencies. Few guidelines are given below to approach the, problems., Assess the urgency of the situation. Before you report an, emergency, make sure that the situation is genuinely urgent. Call for emergency services if you believe that a, situation is life-threatening or otherwise extermely disruptive., , P & M : Fitter - Related Theory for Exercise 1.1.06, , Copyright Free Under CC BY Licence, , 23
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•, , •, , A fire - If you're reporting a fire, describle how the fire, started and where exactly it is located. If someone, has already been injured, missing, report that as well., A life - threatening medical emergency, explain how, the incident occured and what symptoms the person, currently displays., , Report your location, The first thing the emergency dispatcher will ask where, you are located, so the emergency services can get there, as quickly as possible. Give the exact street address, if, you're not sure of the exact address, give approximate, information., , Call emergency service, The emergency number varies - 100 for Police & Fire, 108, for Ambulance., , 24, , P & M : Fitter - Related Theory for Exercise 1.1.06, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.07, , Operation of electrical mains/ Circuit breakers and electrical safety, Objectives : At the end of this lesson you shall be able to, • understand the operation of electrical mains/circuit breaker, • state the importance of electrical safety., Electrical safety, , – Switch off the electric power,insulate yourself and pull, away the person from the electrical contact, , Electric shock, If a person happens to come in contact with an electrical, live wire and if he has not insulated himself, then electric, current flows through his body. Since the human body, cannot withstand current flow more than a few tens of, milliamps, the human body suffers a phenomenon generally, known as electric shock. Electric shock may turn out to, be hazardous to some of the parts of the human body and, some times even to the life of the person., The severity of an electric shock depends on:, – the level of current passing through the body, – how long does the current keep passing through the, body., Therefore, the higher the current or longer the time, the, shock may result in a causality., In addition to the above factors, other factors which, influences the severity of shock are:, – age of the person receiving a shock, – surrounding weather condition, – condition of the floor (wet or dry), – voltage level of electricity, – insulating property of the footwear or wet footwear, and, so on., Effects of electric shock, The effect of electric shock at very low voltage levels (less, than 40 V) may only be an unpleasant tingling sensation., But this shock itself may be sufficient to cause someone, to lose his balance and fall, resulting in casualty., At higher voltage levels the muscles may contract and the, person will be unable to break off from the contact by, himself. He may lose consciousness. The muscles of the, heart may contract spasmodically (fibrillation). This may, even turn out to be fatal., At an excessive level of voltage, the person receiving a, shock may be thrown off his feet and will experience severe, pain and possibly burns at the point of contact. This in, most cases is fatal., Electric shock can also cause burning of the skin at the, point of contact., Action to be taken in case of an electric shock, If the victim of an electric shock is in contact with the, supply, break the contact the victim is making with the, electricity by any one or more of the following., , or, Remove the mains electric plug. Avoid direct contact with, the victim. Wrap your hands using dry cloth or paper, if, rubber gloves are not available., or, Remove the electric contact made by wrenching the, cable/equipment/point free from contact using whatever, is at hand to insulate yourself such as a wooden bar,, rope, a scarf, the victim’s coat-tails, any dry article of, clothing, a belt, rolled up newspaper, non-metallic hose,, PVC tubing, baked paper, tube etc. and break the contact by pushing or pulling the person or the cable/equipment/point free, or, Stand on some insulating material such as dry wood, rubber or plastic, or whatever is at hand to insulate yourself, and break the contact by pushing or pulling the person or, the cable/equipment/point free., If you are uninsulated, do not touch the victim, with your bare hands. Otherwise you also will, get a shock and become a victim., If the victim is aloft(working on a pole or at raised place),, take suitable measures to prevent him from falling or, atleast ensure that his fall is safe., Treatment to be given for the victim of electric shock, Electric burns on the victim may not look big/large. But it, may be deep rooted. Cover the burnt area with a clean,, sterile dressing. Get a doctor’s help to treat him as quickly, as possible., If the victim is unconscious after an electric shock, but is, breathing, carry out the following first aid:, – loosen the clothing at the neck, chest and waist, – place the victim in the recovery position., – Keep a constant check on the breathing and pulse rate., If you find them feeble, immediately give artificial, respiration and press the lower rib to improve the, heartbeat., – Keep the casualty warm and comfortable., – Send for a doctor immediately., , 25, , Copyright Free Under CC BY Licence
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Do not give an unconscious person anything, through the mouth., Do not leave a unconscious person unattended., A person having received electric shock may, also have burn injuries. DO NOT waste time by, applying first aid to the burns until breathing, has been restored and the patient can breathe, normally unaided., Treatment to be given in case of burns, severe, bleeding, Burns caused due to electrical shock are very painful. If a, large area of the body is burnt, clean the wound using clear, water, or with clean paper, or a clean shirt. This treatment, relieves the victim of pain. Do not give any other treatment, on your own. Send for a doctor for further treatment., A wound which is bleeding profusely, especially in the, wrist, hand or fingers must be considered serious and, must receive a doctor’s attention. As an immediate first aid, measure, carry out the following;, – make the patient lie down and rest, – if possible, raise the injured part above the level of the, body as shown in Fig 1., , If the wound is in the abdominal area (stab wound), caused, by falling on a sharp tool, keep the patient bending over the, wound to stop internal bleeding., General procedural steps to be adopted for treating, a person suffering from an electrical shock, 1 Observe the situation. Choose the appropriate, method(listed in earlier paragraphs) to release the, person from electrical contact., Do not run to switch off the supply that is far, away or start searching for the mains switch., 2 Move the victim gently to the nearest ventilated place., 3 Check the victim’s breathing and consciousness. Check, if there are injuries in the chest or abdomen. Give artificial, respiration/applying pressure on the heart if found, necessary (refer in this lesson/exercise)., , Squeeze together the sides of the wound as shown in, Fig 2. Apply pressure as long as it is necessary to stop, the bleeding., , Use the most suitable method of giving artificial, respiration depending upon the injuries if any, on the chest/abdomen., 4 Send for a doctor., Till the doctor arrives, you stay with the victim, and render help as best as you can., 5 Place the victim in the recovery position., 6 Cover the victim with a coat, socks or any such thing to, keep the victim warm., , When the bleeding stops temporarily, put a dressing over, the wound using sterilized cotton, and cover it with a pad, of soft material as shown in Fig 3., , 26, , Actions listed above must be taken syst, ematically and briskly. Delay in treating the, patient may endanger his life., , P & M : Fitter - Related Theory for Exercise 1.1.07, , Copyright Free Under CC BY Licence
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Area of control of switches - operation on emergency, Objectives : At the end of this lesson you shall be able to, • explain the term 'emergency', • explain the need to switch off the circuit during emergency, • explain the method of locating the area sub-main and switches in the shop floor, • explain the position of handle with respect to ON & OFF in case of iron clad switches, MCB and ordinary house, hold sitches., An emergency is an unexpected occurrence and requires, immediate action. In a place like a workshop such a, situation can arise when a person gets a shock due to, electrical current or a person gets injured by the rotating, part of a machine., , The handle of iron clad switches and the knob of MCB, should be pushed down to switch 'off ' the circuits as shown, in Fig 2. whereas in the ordinary switches, the switch off, the circuit should be done by pushing the switch to upward, position. (Fig 3), , In such situations, switching off the supply will be the first, and best solution to avoid further damage to the victim., For this, every person involved in the workshop should, know which switch controls the area where the victim of, shock remains., Normally the total wiring in a workshop is controlled by a, main switch and the different areas within the workshop, may have two or more sub-main switches as shown in, Fig.1., , To ascertain the area of the sub-main control, switch off, one of the sub-main switches and try to switch 'on' the, lights, fans and power points in that suspected area. If, they do not work, then the area covered by the fan, light, and power points are controlled by the sub-main switch., One after another, switch off the sub-main switches and, locate their area of control. Mark the area of control of the, switch in the plan of the wireman's section., In a well organised workshop, the main switch, the submain, switches and distribution ways will have clear marking to, show their area of control. (Fig 1) If this is not found, do, this now. However, If you are not sure about the area of, control the sub-main of the switches it is always better to, switch 'off' the main switch itself., , The emergency situations could happen even at home, Hence, identify the area of control of the switch and mark, them in the main/sub-main/ distribution bound of your house, switch board as a safety measure. Educate the intimates, of the house how to switch off the circuit in case of any, emergency., , P & M : Fitter - Related Theory for Exercise 1.1.07, , Copyright Free Under CC BY Licence, , 27
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Safety rules on electrical equipments, Objectives : At the end of this lesson you shall be able to, • explain the necessary of adopting the safety rules, • list the safety rules and follow them., •, , Never extend electrical circuits by using temporary, wiring., , •, , Stand on a wooden stool, or an insulated ladder while, repairing live electrical circuits/appliances or replacing, fused bulbs. In all the cases, it is always goog to open, the main switch and make the circuit dead., , •, , Stand on rubber mats while working/ operating switch, panels, control gears etc., , •, , Position the ladder, on fim ground., , The listed safety rules should be learnt, remembered and, practised by every electricaian. Here a electrician should, remember the famous proverb, "Electricity is a good, servant but a bad master"., , •, , While using a ladder, ask the helper to hold the ladder, against any possible slipping., , •, , Always use safety belts while working on poles or high, rise points., , Safety rules, , •, , Never place your hands on any moving part of rotating, machine and never work around moving shafts or, pulleys of motor or generator with loose shirt sleeves, or dangling neck ties., , •, , Only after identifying the procedure of operation, operate, any machine or apparatus., , •, , Run cables or cords through wooden partitions or floor, after inserting insulating procelain tubes., , •, , Connections in the electrical appratus should be tight., Lossely connected cables will heat up and end in fire, hazards., , •, , Use always earth connection for all electrical appliances, along with 3-pin sockets and plugs., , Use only correct capacity fuses in the circuit. If the, capacity is less it will blow out when the load is, connected. If the capacity is large, it gives no protection, and allows excess current to flow and endangers men, and machines, resulting in loss of money., , •, , While working on dead circuits remove the fuse grips;, keep them under safe custody and also display 'Men, on line' board on the switchboard., , •, , Do not meddle with inter locks of machines/switch gears, , •, , Replace or remove fuses only after switching off the, circuit switches., , •, , Do not connect earthing to the water pipe lines., , •, , Do not use water on electrical equipment., , •, , Use extension cords with lamp guards to protect lamps, against breakage and to avoid combusitble material, coming in contact wih hot bulbs., , •, , Discharge static voltage in HV lines/equipment and, capacitors before working on them., , •, , Use accessories like sockets, plugs and switches and, appliances only when they are in good condition and, be sure they have the mark of BIS (ISI). (Necessity, using BIS (ISI) marked accessories is explained under, standardisation., , Safety rules, Necessity of safety rules: Safety consciousness is one, of the essential attitudes required for any job. A skilled, electrican always should strive to form safe working habits., Safe working habits always save men, money and material., Unsafeworking habits always end up in loss of production, and profits, personal injury and even death. The safety hints, given below should be followed by Electrican to avoid, accidents and electrical shocks as his job involves a lot of, occupational hazards., , •, , Only qualified persons should do electrical work, , •, , Keep the workshop floor clean, and tools in good, condition., , •, , Do not work on live circuits, if unavoidable, use rubber, gloves rubber mats, etc., , •, , Use wooden or PVC insulated handle screwdrivers, when working on electrical circuits., , •, , Do not touch bare conductors., , •, , When soldering, place the hot soldering irons in their, stand. Never lay switched 'ON' or heated soldering iron, on a bench or table as it may cause a fire to break out., , •, , 28, , P & M : Fitter - Related Theory for Exercise 1.1.07, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.08, , Safety practice - fire extinguishers, Objectives : At the end of this lesson you shall be able to, • state the effects of a fire breakout, • state the causes for fire in the workshop, • state the conditions required for combustion relevant to fire prevention, • state the general precautionary measures to be taken for fire prevention., Fire is the burning of combustible material. A fire in an, unwanted place and on an unwanted occasion and in, uncontrollable quantity can cause damage or destroy, property and materials. Fires injure people, and sometimes,, cause loss of life. Hence, every effort must be made to, prevent fire. When a fire outbreak is discovered, it must be, controlled and extiguished by immediate correct action., Is it possible to prevent fire? Yes, by eliminating anyone of, the three factors that cause fire. (Fig 1), , Preventing fires, The majority of fires begin with small outbreaks which burn, unnoticed until they become big fires of uncontrollable, magnitude. Most of the fires could be prevented with more, care and by following some rules of simple commonsense., Accmulation of combustible refuse (cotton waste soaked, with oil, scrap wood, paper, etc.) in odd corners are of fire, risk. Refuse should be removed to collection points., The cause of fire in electrical equipment is misuse or, neglect. Loose connetions, wrongly rated fuses or cables,, overloaded circuits cause over heating which may in turn, lead to fire. Damage to insulation between conductors in, cables also causes fire., Clothing and anything else which might catch fire should, be kept well away from heaters. Make sure the heater is, shut off at the end of a working day., , The factors that must be present in combination for a fire, to continue to burn are as followes., Fuel, , Heat, , Oxygen, , Any substance, liquid, solid, or gas will, burn if given oxygen and high enough, temperature., Every fuel will begin to burn at a certain, temperature. Solids and liquids give off, vapour when heated and it is this vapour, which ignites. Some liquids give off, vapour even at normal room temperature, say 15oC,eg. petrol., Usually it exists in sufficient quatity in, air to keep a fire burning., , Extinguishing of fires, lsolating or removing any of these factors from the, combination will extinguish the fire. There are three basic, ways of achieving this., •, , Starving the fire of fuel by removing the fuel in the vicinity, of fire., , •, , Smothering - i.e by isolating the fire from the supply of, oxygen by blanketing it with foam, sand etc., , •, , Cooling - i.e. by using water to lower the temperature., , Highly flammable liquids and petroleum mixtures (Tinner,, Adhesive solutions, Solvents, Kerosene, Spirit, LPG Gas, etc.) should be stored in a separated place called the, flammable material storage area., Blowlamps and torches must not be left burning when, they are not in use., Classification of fires, extinguishing agents., , and, , recommended, , Fire are classified into four types in terms of the nature of, fuel., Different types of fire have to be dealt with different ways, and with different extiguishing agents., An agent is the material or substance used to put out the, fire, and is usually (but not always) contained in a fire, extinguisher with a mechanism for spraying into the fire., It is important to know the right type of agent for a particular, type of fire using the worng one can make things worse., There is no classification for 'electrical fires' as such since, these are only fires in materials where electricity is present., , 29, , Copyright Free Under CC BY Licence
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Fuel, , Extinguishing, , CLASS 'A' Fire, , Wood, paper, cloth etc, Solid materials, , Most effective i.e. cooling with water. Jets of, water should be sprayed on the base of the fire, and then gradually upwards., , CLASS 'B' Fire, , Flammable liquid., liquitiable solids, , Should be smothered. The aim is to cover the, entire surface of the burning liquid. This has the, effect of cutting off the supply of oxygen to the, fire., Water should never be use on burning liquids., Foam, dry powder or CO2 may be used on this, type of fire., , CLASS 'C' Fire, , Gas and liquified gas, , Extreme caution is necessary in dealing with, liquified gases. There is a risk of explosion and, sudden spreading of fire in the entire vicinity. If an, appliance fed from a cylinder catches fire - shut, off the supply of gas. The safest course is to raise, an alarm and leave the fire to be dealt with by, trained personnel., Dry powder extinguishers are used on this type, of fire., Special powders have now been developed which, are capable of controlling and/or extinguishing, this type of fire, , CLASS 'D' Fire, , Involving metals, , The standard range of fire extinguishing agents, is inadequate or dangerous when dealing with, metal fires., Fire on electrical equipment., Carbon dioxide, dry powder and vapourising, liquid (CTC) extinguishers can be used to deal, with fires in electrical equipment. Foam or liquid, (e.g Water) extinguisher must not be used on, electrical equipment under any circumstances., , 30, , P & M : Fitter - Related Theory for Exercise 1.1.08, , Copyright Free Under CC BY Licence
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Types of fire extinguishers, Objectives : At the end of this lesson you shall be able to, • distinguish different types of fire extinguishers, • determine the correct type of fire extinguisher to be used based on the class of fire, • descirbe the general procedure to be adopted in the event of a fire., A fire extinguisher, flame extinguisher or simply, extinguisher is an active fire protection device used to, extinguish or control small fires, often in emergency, situation.It is not intended for use on and out off control fire., , Must not be used where electrical equipment is involved., , Many types of fire extiguishers are available with differetnt, extinguishing 'agents' to deal with different classes of fires., (Fig 1), , Dry powder extinguishers (Fig 4), , Water-filled extinguishers, There are two methods of operation. (Fig 2), - Gas cartridge type, - Stored pressure type, , Extinguishers fitted with dry powder may be of the gas, cartridge or stored pressure type. Appearance and method, of operation is the same as that of the water-filled one. The, main distinguishing feature is the fork- shaped nozzle., Powders have been developed to deal with class D fires., Carbon dixide (Co2), This type is easliy distinguished by the distinctively shaped, discharge horn. (Fig 5), , With both methods of operation the discharge can be, interrupted as required, conserving the contact and, preventing unnecessary water damage., Foam extinguishers (Fig 3), These may be of stored pressure or gas cartridge types., Always check the operating instructions on the, extinguisher before use., Foam extinguishers are most suitable for:, - flammable liquid fires, - running liquid fires, , Suitable for class B fires. Best suited where contamination, by deposits must be avoided. Not generally effective in, open air., 31, P & M : Fitter - Related Theory for Exercise 1.1.08, , Copyright Free Under CC BY Licence
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Always check the operating instructions on the container, before use, available with different gadgets of operation, such as -plunger, lever trigger etc., , The fumes given off by these extiguishers are, dangerous, expecially in confined space., General procedure to be adopted in the event of a fire to, be adopted., , Halon extinguishers (Fig 6), , – Raise an alarm., – Turn off all machinery and power (gas and electricity)., – Close the doors and windws, but do not lock or bolt, them. This will limit the oxygen fed to the fire and, prevent its spreading., – Try to deal with the fire if you can do so safely. Do not, take risk, getting in trapped., , Theses extinguishers may be filled with carbon tetrachloride, and bromochlorodifluoro methene (BCF)., , – Anybody not involved in fighting the fire should leave, calmly using the emergency exits and go to the, designated assembly point. Failure to do this may, mean that some person is unaccounted for and others, may have to put themselves to the trouble of searching, for him or her at risk to themselves., , They may be of either gas cartridge or stored pressure, type., They are more effective in extinguishing small fires involving, pouring liquids. These extinguishers are particularly suitable, and safe to use on electrical equipment as the chemicals, are electrically non-conductive., , Working on fire extinguishers, Objectives : At the end of this lesson you shall be able to, • state about the selection of the fire extinguishers according to the type of fire, • state the method of operation of the fire extinguishers, • explain how to extinguish the fire., •, , Alert people surrounding by shouting fire, fire, fire when, observe the fire (Fig 1a& b), , •, , Open emergency exit and ask them to go away., (Fig 1d), , •, , Inform fire service or arrange to inform immediately., (Fig 1c), , •, , Put "off" electrical power supply., , 32, , Don't allow people to go nearer to the fire, , P & M : Fitter - Related Theory for Exercise 1.1.08, , Copyright Free Under CC BY Licence
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•, , Analyze and identify the type of fire. Refer Table 1., Table 1, Class 'A', , Wood, paper, cloth,, soild material, , Class 'B", , Oill based fire (grease, gasoline, oil) liquefiable, gases, , Class 'C', , Gas and liquefiable, gases, , Class 'D', , Metals and electrical, equipment, , Assume the fire is 'B' Type (flammable liquifable solids), •, , Select CO2 (Carbon di oxide) fire extinguisher., , •, , Locate and pick up co2 fire extinguisher. Click for its, expiry date., , •, , Break the seal (Fig 2), , •, , Pull the safety pin from the handle (Pin located at the, top of the fire extinguisher) (Fig 3), , P & M : Fitter - Related Theory for Exercise 1.1.08, , Copyright Free Under CC BY Licence, , 33
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•, , Aim the extinguisher nozzle or hose at the base of the, fire (this will remove the source of fuel fire) (Fig 4), Keep your self low, , Fire extinguishers are manufactured for use, from the distance., Caution, , •, , Squeeze the handle lever slowly to discharge the agent, (Fig 5), , •, , Sweep side to side approximately 15 cm over the fuel, fire until the fire is put off (Fig 5), , •, , While putting off fire, the fire may flare up, , •, , Do not be panicked before it is put off, promptly., , •, , If the fire doesn't respond well after you, have used up the fire extinguisher move, away yourself away from the fire point., , •, , Do not attempt to put out a fire where it is, emitting toxic smoke leave it for the, professionals., , •, , Remember that your life is more important, than property. So don't place yourself or, others at risk., , In order to remember the simple operation of, the extinguisher, remember P.A.S.S. This will, help you to use the fire extinguisher., P for Pull, A for Aim, S for Squeeze, S for Sweep, , 34, , P & M : Fitter - Related Theory for Exercise 1.1.08, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.09, , Safety, health and environment guidelines, Objectives : At the end of this lesson you shall be able to, • state safety, health and environment guidelines., • state various section provided in factories act, 1948 on occupational safety and health., Safety, Health and Environment guidelines as per, , 24, , The Indian Electricity Rules, 1956, , Rules & requlations followed in india are listed as follows:, , 25, , The Petroleum Act, 1934, , 1, , The Enivironment (Protection) Act, 1986, , 26, , The Petroleum Rules,1976, , 2, , The Environment (Protection) Rules, 1986, , 27, , The Public Liability Insurance Act, 1991, , 3, , Enivironmental Impact Assessment of Development, Projects 1994, , 28, , The Public Libility Insurance Rules, 1991, , 29, , 4, , The Prevention and control of pollution (uniform consent, procedure) Rules,1999, , Hazardous Wastes (Management and Handling), Rules,2000, , 5, , Manufacture, Storage and Import of Hazardous, chemicals Rules, 1989, , 6, , Manufacture, Storage and Import of Hazardous, chemical (Amendment ) Rules, 2000, , 7, , Hazardous Wastes (Management and Handling), Rules, 1989, , 8, , Bio-Medical Waste (Management and Handling), Rules, 1998, , Poor working conditions affect a worker's health and, safety. Unsafe or unhealthy working conditions are not, eliminated to industries and can be anywhere. Whether, inside or outside, the workshop workers may face many, health and safety hazards. It also affects the environment, of the workers. Occupational hazards have harmful effects, on workers, their families, and other people in the, community, as well as on the physical environment around, the workplace., , 9, , Batteries (Management & Handling ) Rules, 2000, , The provisions made in as applicable to the Factories Act,, 1948 (Act No.63 of 1948), as amended by the Factories, (Amendment) Act, 1987 (Act 20 of 1987) are as follows:, , 10, , Ozone Depleting Substances (Regulation) Rules,, 2000, , Occupational safety and health, , 11, , The Air (Prevention and Control of Pollution) Act, 1981, as amended by Amendment Act, 1987, , various sections provided in factories act, 1948 are under, the following headings:, , 12, , The Air (Prevention and Control of Pollution) Act, 1982, , •, , Fencing of machinery, , 13, , The Air (Prevention and Control of Pollution) Rules,, 1982, , •, , Work on or near machinery in motion, , •, , Employment of young persons on dangerous machines, , 14, , The Tamil Nadu Air (Prevention and Control of Pollution), Rules, 1983, , •, , Striking gear and devices for cutting off power, , •, , Self-acting machines, , 15, , Noise Pollution (Regulation and Control) Rules, 2000, , •, , Casing of new machinery, , 16, , The Water (Prevention and Control of Pollution) Act,, 1974 as amended in 1978 & 1988, , •, , Prohibition of employment of women and children near, cotton-openers, , 17, , The Tamil Nadu Water (Prevention and Control of, Pollution) Rules,1983, , •, , Hoist and lifts, , 18, , The Water (Prevention and Control of Pollution) Cess, Act, 1977 as amended by Amendment Act, 1991., , •, , Lifting machines, chains, ropes and lifting tackles, , •, , Revolving machinery, , •, , Pressure plant, , •, , Floors, stairs and means of access, , •, , Excessive weights, , •, , Protection of eyes, , •, , Precautions against dangerous fumes, gases, etc, , 19, , The Water (Prevention and Control of Pollution) Cess, Rules, 1978, , 20, , Factories Act, 1948, , 21, , Tamilnadu Factories Rules, 1950, , 22, , The Gas Cylinders Rules, 1981, , 23, , The Indian Electricity Act, 1910, 35, , Copyright Free Under CC BY Licence
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•, , Precautions regarding the use of portable electric light, , •, , Disposal of wastes and effluents, , •, , Explosive or inflammable dust, gas, etc, , •, , Ventilation and temperature, , •, , Precautions in case of fire, , •, , Dust and fume, , •, , Power to require specifications of defective parts or, test of stability, , •, , Artificial humidification, , •, , Overcrowding, , •, , Safety of buildings and machinery, , •, , Lighting, , •, , Maintenance of buildings, , •, , Drinking water, , •, , Power to make rules to supplement this Chapter, , •, , Latrines and urinals, , •, , Cleanliness, , •, , Spittoon, , 36, , P & M : Fitter - Related Theory for Exercise 1.1.09, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Safety, , Related Theory for Exercise 1.1.10, , Basic understanding on hot work, confined space work and material, handing equipment, Objectives: At the end of this lesson you shall be able to, • state what is hot working, • brief confined space work, • use of material handling equipments., Hot work, , Different types of material handling equipment, , Hot work is defined as forging, gas cutting, welding,, soldering and brazing operations for construction,, maintenance/repair activities., , • Tools, , Hot work fire and explosive hazards. Workers performing, hot work such as welding, gas cutting, brazing, soldering, are exposed to the risk of fires from ignition or flammable, or combustible materials in the space, and from leaks of, flammable gas into the space, from hot work equipment., , • Storage units, , A confined space also has limitted or restricted means for, entry or exist and is not designed for continuous occupancy., It includes but are not limited to tanks, vessels, silos,, storage bins, hoppers, vaults, pits, manholes, tunnels,, equipment housings, duct work, pipelines, etc., Materials handling equipment, Materials handling equipment is a mechanical equipment, used for the movement, storage, control and protection /, protecting of materials, goods and products throughout, the process of manufacturing, distribution, consumption, and disposal., , • Vehicles, • Appliance and accessories, Racks, Pallet racks, drive-through or drive-in racks, push back, racks, and sliding racks., Truck/Trolley, Conveyor system, , • Fork lift, • Cranes, • Pallet truck, , Lifiting and handling loads, Objectives : At the end of this lesson you shall be able to, • state the types of injury caused by the improper method of lifting and carrying loads and how to prevent them, • state the 6 points in the process of manual lifting methods., Many of the accidents reported involve injuries caused by, lifting and carrying loads. An Electrician may need to, install motors, lay heavy cables, do wiring, which may, involve a lot of lifting and carrying of loads. Wrong lifting, techniques can result in injury., A load need not necessarily be very heavy to cause injury, The wrong way of lifing may cause injury to the muscles, and joints even though the load is not heavy., Further injuries during lifting and carrying may be caused, by tripping over and object and falling or striking an object, with a load., Type of injury and how to prevent them?, Cuts and abbrasions, Cuts and abbrasions are caused by rough surfaces and, jagged edges:, By splinters and sharp or pointed projections. (Fig 1), , Leather hand gloves will usually be suffcient for protection,, but the load should be checked to make sure of this, since, large or heavy loads may invovle body contact as well., Crushing of feet or hands, Feet or hands should be so postioned that they will not be, trapped by the load. Timber wedges can used when raising, and lowering heavy loads to ensure fingers and hands are, not caught and crushed., 37, , Copyright Free Under CC BY Licence
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Safety shoes with steel toe caps will protect feet (Fig 2), , It will also depend on whether one is used to lifting and, handling heavy loads., What makes an object diffcult to lift and carry?, 1 Weight is not the only factor which makes it difficult to, lift and carry., 2 The size and shape can make an object awkward to, handle., 3 Loads high require the arms to be extended in front of, the body, place more strain on the back and stomach., , Strain to muscles and joints, Strain to muscles and joints may be result of:, , 4 The absence of hand holds or natural handling points, can make it diffcult to raise and carry the object., , -, , Correct manual lifting techniques, , Lifting a load which is too heavy, or of lifting incorrectly., , Sudden and awkward movements such as twisting or jerking, during a lift can put severe strain on muscles., , 1 Approach the load squarely, facing the direction of travel, , Stop lifting'-lifting from a standing postion with the back, rounded increases the chance of back injury., , 2 The lift should start with the lifter in a balanced squatting, position, with the legs slightly apart and the load to be, lifited held close to the body., , The human spine is not an effcient weight lifing machine, and can be easily damaged if incorrect techniques are, used., , 3 Ensure that a safe firm hand grip is obtained. Before, the weight is taken, the back should be straightended, and held as near the vertical position as possible. (Fig4), , The stress on a rounded back can be about six, times greater than if the spine is kept straight., Fig 3 shows and example of stoop lifting., , 4, , To raise the load, first straighten the legs. This ensures, that the lifting strain is being correctly transmitted and, is being taken by the powerful thigh muscles and bones., , 5, , Look directly ahead, not down at the load while, straightening up, and keep the back straight, this will, ensure a smooth, natural movement without jerking or, straining (Fig 5), , 6, , To complete the lift, raise the upper part of the body to, the vertical position. When a load is near to an, individual's maximum lifting capacity it will be necessay, to lean back on the hips slightly (to counter balance, the load) before straightening up.(Fig 6), , Preparaing to lift, Before lifting or handling any load ask youself the following, questions., What has to be moved?, Where from and where to?, Will assistance be required?, Is the route through which the load has to be moved is, clear of obstacles?, Is the place where the load has to be kept after moving is, clear of obstacles?, Load which seems light enough to carry at first will become, progressively heavier, the farther you have to carry it., The person who carries the load should always be able to, see over or around it., The weight that a person can lift will vary according to:, -, , Age, , -, , Physique, and, , -, , Condition, , 38, , P & M : Fitter - Related Theory for Exercise 1.1.10, , Copyright Free Under CC BY Licence
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Keeping the load well near to the body, carry it to the, place where it is to be set down. When turning, avoid, twisting from the waist- turn the whole body in one, movement., Lowering the load, Make sure the area is clear of any obstructions. (Fig 7), Bend the knees to a semi- squattting position, keep the, back and head erect by looking straight ahead, not down, at the load. It may be helpful to rest the elbows on the, thighs during the final stage of lowering., , Moving heavy equipment, Objectives: At the end of this lesson you shall be able to, • name the methods followed in industry to move heavy equipment, • describe the procedure to be followed for moving heavy equipment on layers and rollers, • list the safety consideration while raising a load and moving a load., Heavy equipements are moved in industry using any of, the following methods., , Examine the steel rope sling for any cut,, abrasion, wear fraying or corrosion., , Crane and slings, , Damaged slings must not be used., , Winches, Machine moving platforms, , Distribute the weight as evenly as possible between the, slings when using more than one sling. (Fig 1), , Layers and rollers, , Keep the slings as near to vertical as possible., , Using crane and slings, , Winches, , This method is used whenever loads are to be lifted and, moved. (Fig 1), , Winches are used to pull heavy loads along the ground., They may be power-driven (Fig 2) or hand operated. (Fig3), , P & M : Fitter - Related Theory for Exercise 1.1.10, , Copyright Free Under CC BY Licence, , 39
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For unloading follow the procedure in the reverse order., Using layers and rollers, Sometimes a load cannot be moved along the ground, because of the irregular shape of its base or because it is, not rigid enough., Place such a load on a flat-bottomed pallet or 'layer' resting, on the round bars. (Fig 5), , Ensure that the safe working load (SWL) of the winch is, adequate for the task., Secure the winch to a structure which is strong enough, to withstand the pull., On open ground, drive long stakes into the ground and, secure the winch to them., Choose a suitable sling and pass it around the base of, the load. Secure it to the hook of the winch., , Ensure the bars (rollers) are long enough to project at, each side of the load, for ease of handling., , Some heavy items have special lugs welded, to them for jacking and towing purposes., , They should be large enough to roll easily over any uneven, surface along the route but should be small enough to be, handled easily., , Safety consideration, Before using any winch, check that the brake, and ratchet mechanism are in working order., Practise how to use the brakes., Keep hands and fingers well away from the gear wheels., Keep the bearings and gears oiled or greased., Machine moving platforms, This is a special device made to move heavy equipment, in industry. Fig 4 shows the method of loading a heavy, transformer., , Two or three bars of equal diameter are, sufficient for most loads but if four or more, are used, the load may be moved faster as, there is no delay when moving the rear bar to, the front. (Fig 5), Move the load by using a crowbar as shown in Fig 6., Keep the crowbar at the end of the pallet with an angle, and a firm grip on the ground. Apply the force at the top of, the bar as shown., , Caution, When a load is on rollers, only shallow slopes, can be negotiated., Hold the load in check all the time if it is on, the slope., Use a winch with an effective brake for this, operation., Pass a suitable sling round the load at a convenient height., Attach the sling to the hook of the winch and draw the, load on the platform until its centre of gravity lies between, the front and rear wheels., , To negotiate a corner on rollers, For a moderate load, insert one roller a little larger in, diameter than the others as the corner is approached., , Lower the jacks so that the platform rests on its wheels., 40, , P & M : Fitter - Related Theory for Exercise 1.1.10, , Copyright Free Under CC BY Licence
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When this roller is under the centre of gravity of the load,, the load can be rocked to and fro on the roller and swivelled, around sideways. (Fig 7), , Safety consideration, Moving heavy loads with crowbars or jacks, Make sure your hands are clear of the load before lowering, it on to the packing or rollers., Do not use your hands underneath the packing when, positioning it. Use a push block., Place the packing on the floor and push it under the load., (Fig 10), Hold it by its side faces keeping the fingers well away, from the lower edge of the load and from the floor. (Fig 10), , For heavier loads, Stop the load on the roller at the beginning of the corner., Twist the load round on the rollers by pushing the sides, with crowbars until the load is just over the ends of the, rollers. (Fig 8), , Raising a load, Check that the slings are correctly secured to the load, and to the hook. Ensure they are not twisted or caught on, a projecting part of the load., Before starting to lift a load, if you cannot see an assistant, on the far side of the load, verify that he is ready to lift the, load and ensure that his hands are clear of the slings., Warn nearby workers that the lifting is about to begin., Place some rollers at an angle to the front of the load., (Fig 9), , Lift slowly., Take care to avoid being crushed against other objects as, the load rises. (Fig 11) It may swing or rotate as it leaves, the ground., , Push the load forward on to these rollers., Twist the load further round and place the freed rollers in, front of and at an angle to the load., Continue until the load is pointing in the desired direction., , Minimise such movement by locationg the hooks as, accurately as possible above the centre of gravity of the, load., Keep the floor clear of unnecessary objects., , P & M : Fitter - Related Theory for Exercise 1.1.10, , Copyright Free Under CC BY Licence, , 41
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Moving a load, Check that there are no obstacles in the way of the crane, and load. (Fig 12), , Ensure that the load will not pass over the head of other, people. (Fig 13), , Stand clear off the load and move it steadily., Be prepared to stop the load quickly if somebody moves, into its path., Allow for the natural swing of the load when changing speed, or direction., , 42, , The tackle or sling may fall or slip., Warn other workers to stand clearly away from, the route of the load., Remember that accidents do not happen, they are caused., , P & M : Fitter - Related Theory for Exercise 1.1.10, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.11, , Linear measurement, Objectives: At the end of this lesson you shall be able to, • name the base unit of linear measurement as per the International System of units of measurement (SI), • state the multiples of a metre and their values, • state the purpose of steel rule, • name the types of steel rule, • state the precautions to be followed while using a steel rule., When we measure an object, we are actually comparing, it with a known standard of measurement., The base unit of length as per SI is METRE., Length - SI UNITS and MULTIPLES, Base unit, The base unit of length as per the Systems International, is metre. The table given below lists some multiples of a, metre., METRE(m), , The British system of length measurement, An alternative system of length measurement is the British, system. In this system, the base unit is the Imperial, Standard Yard. Most countries, including Great Britain, itself, have, however, in the last few years, switched over, to SI units., Engineer’s steel rule (Fig 3) are used to measure the, dimensions of work pieces., , = 1000 mm, , CENTIMETRE (cm) = 10 mm, MILLIMETRE (mm) = 1000μ, MICROMETRE (μm) = 0.001 mm, Measurement in engineering practice, Usually, in engineering practice, the preferred unit of length, measurement is millimetre. (Fig 1), , Steel rules are made of spring steel or stainless steel., These rules are available in length 150mm, 300mm and, 600mm. The reading accuracy of steel rule is, 0.5 mm and 1/64 inch., For accurate reading it is necessary to read vertically to, avoid errors arising out of parallax. (Fig 4), , Both large and small dimensions are stated in millimetres., (Fig 2), , Steel rule in English measure, they can also be available, with metric and English graduation in a complete range of, sizes 150, 300, 500 and 1000 mm. (Fig 5), , 43, , Copyright Free Under CC BY Licence
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The rules are easily inserted in the slotted end of the holder, and are rigidly clamped in place by a slight turn of the, knurled nut at the end of the handle. Five rule lengths are, provided 1/4", 3/8", 1/2", 3/4" and 1" and each rule is, graduated in 32nds on one side and 64ths on the reverse, side., Steel rule with tapered end, This rule is a favorite with all mechanics since its tapered, end permits measuring of inside size of small holes, narrow, slots, grooves, recesses etc. This rule has a taper from 1/, 2 inch width at the 2 inch graduation to 1/8 inch width at, the end. (Fig 8), , Other types of rule, – narrow steel rules, – short steel rules, – full flexible steel rule with tapered end., Narrow steel rule, Narrow steel rule is used to measure the depth of keyways and depth of smaller dia, blind holes of jobs, where, the ordinary steel rule can not reach. Its width is, approximately 5 mm and thickness 2 mm. (Fig 6), , For maintaining the accuracy of a steel rule, it is important, to see that its edges and surfaces are protected from, damage and rust., , Short steel rule (Fig 7), , Do not place a steel rule with other cutting, tools. Apply a thin layer of oil when not in use., Angular measurement, Angular measurement of angles of an object is usually, expressed in degrees, minutes and seconds. One degree, is divided into 60 minutes and one minute is to 60 seconds., Measurements of fundamental, derived units, , This set of five small rules together with a holder is, extremely useful for measurements in confined or hard to, reach locations which prevent the use of ordinary steel, rules. It is used suitably for measuring grooves, short, shoulder, recesses, key ways etc. in machining operation, on shapers, millers and tool and die work., , Measurement of length, Metric, , 44, , British, , Micron, , 1μ, , = 0.001 mm, , Thousand of an inch, , = 0.001", , Millimetre, , 1 mm, , = 1000μ, , Inch, , = 1", , Centimetre 1 cm, , = 10 mm, , Foot 1 ft, , = 12", , Decimetre 1 dm, , = 10 cm, , Yard 1yd, , = 3 ft, , Metre 1 m, , = 10 dm, , 1 furlong 1 fur, , = 220 yds, , Decametre 1 dam, , = 10 metre, , 1 mile, , = 8 fur, , th, , P&M : Fitter - Related Theory for Exercise 1.2.11, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.12, , Scribers, Objectives: At the end of this lesson you shall be able to, • state the features of scribers, • state the uses of scribers., Scribers, In lay out work it is necessary to scribe lines to indicate, the dimensions of the workpiece to be filed or machined., The scriber is a tool used for this purpose. It is made of, high carbon steel and is hardened. For drawing clear and, sharp lines, the point should be ground and honed, frequently for maintaining its sharpness., , While scribing lines, the scriber is used like a pencil so that, the lines drawn are close to the straight edge. (Fig 2), Scriber points are very sharp; therefore, do not put the plain, scriber in your pocket., Place a cork on the point when not in use to, prevent accidents., , Scribers are available in different shapes and sizes. The, most commonly used one is the plain scriber. (Fig 1), , Dividers, Objectives: At the end of this lesson you shall be able to, • name the parts of a divider, • state the uses of dividers, • state the specifications of dividers, • state the important hints on divider points., Dividers are used for scribing circles, arcs and for, transferring and stepping off distances. (Fig 1,2 and 3), , Dividers are available with firm joints and spring joints., (Figs 1 & 4). The measurements are set on the dividers, with a steel rule. (Fig 2), The sizes of dividers range between 50 mm to 200 mm., , 45, , Copyright Free Under CC BY Licence
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The distance from the point to the centre of the fulcrum, roller (pivot) is the size of the divider. (Fig 4), , For the correct location and seating of the divider point, prick punch marks of 30° are used., , The two legs of the divider should always be of equal length., (Fig 5) Dividers are specified by the type of their joints and, length., , The divider point should be kept sharp in order to produce, fine lines. Frequent sharpening with an oilstone is better, than sharpening by grinding. Sharpening by grinding will, make the points soft., , Datum, Objectives: At the end of this lesson you shall be able to, • state the need for datum while marking, • name the different datum references., Say, the height of a person is measured from the floor on, which he stands, the floor then becomes the datum or the, common basis for measurement., A datum is a reference surface, line or point, and its, purpose is to provide a common position from which, measurements may be taken. The datum may be an edge, or centre line depending on the shape of the work. For, positioning a point, two datum references are required., (Figs 1, 2 and 3), , Marking tables, surface plates angle plates, ‘V’ blocks,, and parallel blocks serve as a datum. (Figs 4 & 5), , 46, , The datum references are indicated in the, drawing. The same datum references must, be used for transferring dimensions to the, work-piece., , P&M : Fitter - Related Theory for Exercise 1.2.12, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.13, , Calipers, Objectives: At the end of this lesson you shall be able to, • name the commonly used calipers, • state the advantages of spring joint calipers., Calipers are indirect measuring instruments used for, transferring measurements from a steel rule to a job, and, vice versa., Calipers are classified according to their joints and their, legs., Joint, – Firm joint calipers (Fig 1a), – Spring joint calipers (Fig 1b), , Calipers are used along with steel rules, and the accuracy, is limited to 0.5 mm; parallelism of jobs etc. can be checked, with higher accuracy by using calipers with sensitive feel., , Legs, – Inside caliper for internal measurement. (Fig 2 ), – Outside caliper for external measurement. (Fig 3), , Spring joint calipers have the advantage of quick setting, with the help of an adjusting nut. For setting a firm joint, caliper, tap the leg lightly on a wooden surface., , Jenny calipers, Objectives: At the end of this lesson you shall be able to, • state the uses of a jenny caliper, • state the two types of legs of a jenny caliper., Jenny calipers have one leg with an adjustable divider point,, while the other is a bent leg. (Fig 1) These are available in, sizes of 150 mm, 200 mm, 250 mm and 300 mm., , Jenny calipers are used, – for marking lines parallel to the inside and outside, edges (Fig 2), , 47, , Copyright Free Under CC BY Licence
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- for finding the centre of round bars. (Fig 3), , These calipers are available with the usual bent leg or with, heel., Calipers with bent leg (Fig 2B) are used for drawing lines, parallel along an inside edge, and the heel type (Fig 2A) is, used for drawing parallel lines along the outer edges., The other names for this caliper are:, - hermaphrodite calipers, - leg and point calipers, - odd leg caliper, , 48, , P&M : Fitter - Related Theory for Exercise 1.2.13, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.14, , Types of marking punches, Objectives: At the end of this lesson you shall be able to, • name the different punches in marking, • state the features of each punch and its uses., Punches are used in order to make certain dimensional, features of the layout permanent. There are two types of, punches. They are centre punch and prick punch made, of high carbon steel, hardened and ground., , The witness marks should not be too close to, one another., , Centre Punch: The angle of the point is 90° in a centre, punch. The punch mark made by this is wide and not very, deep. This punch is used for locating centre of the holes., The wide punch mark gives a good seating for starting the, drill. (Fig 1a), , Prick Punch/Dot punch: The angle of the prick punch is, 30° or 60°. (Fig 1b) The 30° point punch is used for making, light punch marks needed to position dividers. The divider, point will get a proper seating in the punch mark. The 60°, punch is used for marking witness marks and called as, dot punch. (Fig 2), , Hammers, Objectives: At the end of this lesson you shall be able to, • state the uses of an engineer's hammer, • identify the parts of an engineer's hammer, • name the types of engineer's hammer, • specify the engineer's hammer., An engineer's hammer is a hand tool used for striking, purposes while punching, bending, straightening, chipping,, forging or riveting., , Face: The face is the striking portion. A slight convexity is, given to it to avoid digging of the edge. It is used for striking, while chipping, bending, punching, etc., , Major parts of a hammer: The major parts of a hammer, are the head and the handle., , Pein: The pein is the other end of the head. It is used for, shaping and forming work like riveting and bending. The, pein is of different shapes such as:, , Hammer is made of drop-forged carbon steel, while the, wooden handle must be capable of absorbing shock., The parts of a hammer-head are the face (1), pein (2),, cheek (3) and the eyehole (4)., , − ball pein (Fig.2a), − cross-pein (Fig.2b), − straight pein. (Fig 2c), 49, , Copyright Free Under CC BY Licence
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The straight pein is used at the corners. (Fig 7), The face and the pein are case hardened., Cheek: The cheek is the middle portion of the hammerhead. The weight of the hammer is stamped here., This portion of the hammer-head is left soft., Eyehole: The eyehole is meant for fixing the handle. It is, shaped to fit the handle rigidly. The wedges fix the handle, in the eyehole. (Figs 3 and 4), , The ball pein hammer is used for driving a chisel in parting, metal. (Fig 8), , Specification: An engineer's hammers are specified by, their weight and the shape of the pein. Their weight varies, from 125 gms to 750 gms., The weight of an engineer's hammer, used for marking, purposes, is 250 gms., The ball pein hammers are used for general work in a, machine/ fitting shop., Before using a hammer, , Application of hammer pein: The ball pein is used for, riveting. (Fig 5), The cross-pein is used for spreading the metal in one, direction. (Fig 6), 50, , − make sure the handle is properly fitted, − select a hammer with the correct weight suitable for, the job, − check the hammer head and handle whether any crack, is there, − ensure that the face of the hammer is free from oil or, grease., , P&M : Fitter - Related Theory for Exercise 1.2.14, , Copyright Free Under CC BY Licence
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'V' Blocks, Objectives: At the end of this lesson you shall be able to, • state the constructional features of 'v' blocks, • name the types of 'v' blocks and state their uses, • specify 'v' blocks as per B.I.S standard., Constructional features, 'V' Blocks are devices used for marking and setting up, work on machines. The features of the common type of 'V', Blocks are as given in Figs 1 and 2., , The included angle of the VEE is 90° in all cases. 'V', Blocks are finished to a high accuracy in respect of, dimension, flatness and squareness., Types, Different types of 'V' blocks are available. As per BIS,, there are four types, as listed below., Single level single groove 'V' Block (Fig 1), This type has only one 'V' groove, and has single groove, (slots) on either side. These grooves are for, accommodating the holding clamps., Single level double groove 'V' Block (Fig 2), This type will have one 'V' groove, and two grooves (slots), on either side for clamping in two positions., Double level single groove 'V' Block (Fig 3), In this case, the 'V' Block will have two 'V' grooves on the, top and bottom, and a single groove for clamping on either, side., , sets of blocks are used for supporting long shafts parallel, on machine tables or marking off tables., Grades and materials, 'V'Blocks are available in Grade A and Grade B., Grade A 'V' Blocks, These are more accurate, and are available only up to 100, mm length. They are made of high quality steel., Grade B 'V' Blocks, These blocks are not as accurate as the ones in Grade, A. These blocks are used for general machine shop work., These blocks are available up to 300 mm length. These, 'V' Blocks are made of closely grained cast iron., Clamping devices for `V'-Blocks, 'U' clamps are provided for holding cylindrical jobs firmly, on 'V' Blocks. (Fig 6), , Matched pair 'V' Block (Figs 4 and 5), These blocks are available in pairs which have the same, size and the same grade of accuracy. They are identified, by the number or letter given by the manufacturer. These, , Designation, 'V' Blocks are designated by the nominal size (length), and the minimum and maximum diameter of the workpiece, capable of being clamped, and the grade and the number, of the corresponding B.I.S. standard., , P&M : Fitter - Related Theory for Exercise 1.2.14, , Copyright Free Under CC BY Licence, , 51
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Example, A 50 mm long (nominal size) 'V' Block capable of clamping, workpieces between 5 to 40 mm in diameter and of Grade, A will be designated as, 'V' Block 50/5-40 A - I.S.2949., In the case of a matched pair, it will be designated as, 'V' Block M 50/5-40 A I.S.2949., For 'V' Block supplied with clamps, the designation will, be, 'V' Block with clamp 50/5 40 A I.S. 2949., Care and maintenance, , In the case of matched pairs, it should be indicated by the, letter M., For 'V' Blocks with clamps it should be indicated as, 'WITH, CLAMPS'., , •, , Clean before and after use., , •, , Choose the correct size of 'V' block according to the, job requirement., , •, , Apply oil after the use., , Marking off and marking off table, Objectives : At the end of this lesson you shall be able to, • state why marking off is necessary, • state the function of witness marks, • state the features of marking tables, • write the uses of marking tables, • state the maintenace aspects concerning marking tables., Marking off, Marking off or layout is carried out to indicate the locations of operation to be done, and provide guidance during, rough machining or filing., Witness marks, The line marked on metal surfaces is likely to be erased, due to handling. To avoid this, permanent marks are made, by placing punch marks at convenient mark intervals along, the marked line. Punch marks act as a witness against, inaccuracies in machining and hence, they are known as, witness marks., Marking off table (Figs 1 and 2), , Marking tables are of rigid construction with accurately, finished top surfaces. The edges are also finished at right, angles to the top surface., Marking tables are made of cast iron or granite, and are, available in various sizes. These tables are also used for, setting measuring instruments, and for checking sizes,, parallelism and angles., Care and maintenance, A marking table is very precise equiment, and, should be protected from damage and rust., After use, the marking table should be cleaned, with a soft cloth., The Surface of the marking table, made of cast, iron, should be protected by applying a thin, layer of oil., , A marking table (marking-off table) is used as a reference, surface for marking on workpieces., 52, , P&M : Fitter - Related Theory for Exercise 1.2.14, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.15, , Bench vice, Objectives: At the end of this lesson you shall be able to, • state the uses of bench vice, • specify the size of the bench vice, • name the parts of the bench vice, • state the uses of vice clamps., • mention the care and maintenance of vices, Vices are used for holding the workpieces. They are, available in different types. The vice used for bench work, is the bench vice or called Engineer’s vice., A bench vice is made of cast iron or cast steel and it is, used to hold work for filing, sawing, threading and other, hand operations. (Fig 1), , The following are the parts of a vice., Fixed jaw, movable jaw, hard jaws, spindle, handle,, box-nut and spring are the parts of a vice., The box-nut and the spring are the internal parts., Vice clamps or soft jaws (Fig 3), , To hold a finished work use soft jaws (vice clamps) made, of aluminium over the regular jaws. This will protect the, work surface from damage., Do not over-tighten the vice as, the spindle may be, damaged., Care and maintenance of vices, , • Always keep all threaded and moving parts clean by, wiping the vice with a cloth after each use., The size of the vice is stated by the width of the jaws.eg., 150mm parallel jaw bench vice, , • Make sure to oil and lubricate the joints and sliding, , Parts of a bench vice (Fig 2), , • To oil the sliding section, open the jaws completely, , parts., and apply a layer of grease to the screen., , • Remove the rust if appears on the vice using rust remover, chemical., , • When the vice is not in use bring the jaws lightly gap, together and place the handle in a vertical position., , • Avoid striking the handle of the vice by a hammer for, tightening fully, otherwise the handle will become bend, or damaged., , 53, , Copyright Free Under CC BY Licence
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Hacksaw frames and blades, Objectives: At the end of this lesson you shall be able to, • name the different types of hacksaw frames, • specify hacksaw blades, • name the different type of hacksaw blades, • describe the method of sawing, Hacksaw frame: A hacksaw frame is used along with a, blade to cut metals of different sections, and is specified, by the type and maximum length of the blade that can be, fixed., , Parts of a hacksaw blade (Fig 2), , Example, , 3 Centre line, , Adjustable hacksaw frame - tubular - 250 - 300mm or 8" 12", , 4 Pin holes, , 1 Back edge, 2 Side, , Types of hacksaw frames, Solid frame (Fig 1a): Only a blade of a particular standard, length can be fitted to this frame. e.g 300 mm or 250 mm., Adjustable frame (flat type): Different standard lengths, of blades can be fitted to this frame i.e. 250 mm and 300, mm., Adjustable frame (tubular type) (Fig 1b): This is the most, commonly used type. It gives a better grip and control,, while sawing., , Type of hacksaw blades, All-hard blade: The full length of the blade between the, pins is hardened and it is used for harder metals such as, tool steel, die steel and HCS., Flexible blade: Only the teeth are hardened. Because, of their flexibility these blades are useful for cutting along, curved lines. Flexible blades should be thinner than allhard blades., Pitch of the blade (Fig 3): The distance between adjacent, teeth is known as the ‘pitch’ of the blade., Classification, , Pitch, , Coarse, , 1.8 mm, , Medium, , 1.4 mm & 1.0 mm, , Fine, , 0.8 mm, , Parts of a hacksaw frame, 1, , Handle, , 2, , Frame, , 3, , Tubular frame with holes for length adjustment, , 4, , Retaining pins, , 5, , Fixed blade-holder, , 6, , Adjustable blade-holder, , 7, , Wing-nut, , A hacksaw blade is made of either low alloy steel (LA) or, high speed steel (HSS), and is available in standard lengths, of 250 mm and 300mm. (Fig 2), , 54, , Specification: Hacksaw blades are specified by the, length, pitch and type of material. (The width and, thickness of blade is standardised), Example, 300 x 1.8 mm pitch LA all-hard blade., , P&M : Fitter - Related Theory for Exercise 1.2.15, , Copyright Free Under CC BY Licence
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To prevent the hacksaw blade binding when penetrating, into the material, and to allow free movement of the blade,, the cut is to be broader than the thickness of the hacksaw, blade. This is achieved by the setting of the hacksaw teeth., There are two types of hacksaw teeth settings., , Selection of blade: The selection of the blade depends, on the shape and hardness of the material to be cut., Pitch selection (Fig 6): For soft materials such as bronze,, brass, soft steel, cast iron, heavy angles etc. use a 1.8, mm pitch blade., , Staggered set (Fig 4): Alternate teeth or groups of teeth, are staggered. This arrangement helps for free cutting,, and provides for good chip clearance., , For tool steel, high carbon, high speed steel etc. use a, 1.4 mm pitch. For angle iron, brass tubing, copper, iron, pipe etc. use a 1 mm pitch blade. (Fig 7), , Wave set (Fig 5): In this, the teeth of the blade are arranged, in a wave-form. The types of sets for different pictures are, as follows:, For conduit and other thin tubing, sheet metal work etc., use a 0.8 mm pitch. (Fig 8), , Method of sawing, Select the correct blade for the material to be cut., HSS - Blades are used for tough resistant materials, High Carbon Steel - General cutting, , Pitch, , Type of set, , 0.8 mm, , Wave-set, , 1.0 mm, , Wave-set or staggered, , Over 1.0 mm, , Staggered, , For the best results, the blade with the right pitch should, be selected and fitted correctly., , Select the correct number of teeth / inch the general rule, is that atleast 3 teeth should extend across the surface of, the material to be cut., The hand holds the hacksaw handle, and the index finger, is support the handle and also points in the direction of, cutting., The other hand holds the frame, near the wing nut. Cutting/, sewing should be carried out close to the jaws of the vice., This ensures that the metal does not flex or bend under, the force of the hacksaw and the sawing motion., , P&M : Fitter - Related Theory for Exercise 1.2.15, , Copyright Free Under CC BY Licence, , 55
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.16, , Types of vices, Objectives: At the end of this lesson you shall be able to, • state the different types of vices, • state the uses of quick relasing vice, pipe vice, hand vice, pin vice and leg vice., There are different types of vices used for holding workpieces. They are quick releasing vice, pipe vice, hand vice,, pin vice and toolmaker’s vice., , nut on the screw that is fastened to one leg, and passes, through the other., , Quick releasing vice (Fig 1): A quick releasing vice is, similar to an ordinary bench vice but the opening of the, movable jaw is done by using a trigger (lever). If the trigger, at the front of the movable jaw is pressed, the nut, disengages the screw and the movable jaw can be set in, any desired place quickly., , Pin vice (Fig 4): The pin vice is used for holding small, diameter jobs. It consists of a handle and a small collet, chuck at one end. The chuck carries a set of jaws which, are operated by turning the handle., Pipe vice (Fig 2): A pipe vice is used for holding round, sections of metal, tubes and pipes. In the vice, the screw, is vertical and movable. The jaw works vertically., The pipe vice grips the work at four points on its surface., The parts of a pipe vice are shown in Fig 2., Toolmaker’s vice (Fig 5): The toolmaker’s vice is used, for holding small work which requires filing or drilling and, for marking of small jobs on the surface plate. This vice is, made of mild steel., Toolmaker’s vice is accurately machined., , Hand vice (Fig 3): Hand vices are used for gripping screws,, rivets, keys, small drills and other similar objects which, are too small to be conveniently held in the bench vice. A, hand vice is made in various shapes and sizes. The length, varies from 125 to 150 mm and the jaw width from 40 to 44, mm. The jaws can be opened and closed using the wing, , Leg vice, A leg vice is a holding device generally used in a forge shop, for bending and forging work. It is made fo mild steel to avoid, breakage while hammering., , 56, , Copyright Free Under CC BY Licence
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Main pats of a leg vice (Fig 6), The following are the main parts of a leg vice., 1, 2, 3, 4, 5, 6, 7, 8, , Solid jaw, Movable jaw, Threaded jaw, Spindle, Spring, Pivot, Leg, Clamp, , Since the hinged jaw moves in a radial path, the job held in, this vice in not gripped properly because of the line contact., (Fig 7) Hence a work which can be carried out on a bench, vice is not held on a leg vice. Jobs which require hammering, only are held on a leg vice., , P&M : Fitter - Related Theory for Exercise 1.2.16, , Copyright Free Under CC BY Licence, , 57
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.17, , Try square, Objectives: At the end of this lesson you shall be able to, • name the parts of a try square, • state the uses of a try square., The try square (Fig 1) is an instrument which is used to, check squareness (angles of 90°) of a surface., , – mark lines at 90° to the edges of workpieces (Fig 4), , – set workpieces at right angles. (Fig 5), The accuracy of measurement by a try square is about, 0.002 mm per 10 mm length, which is accurate enough, for most workshop purposes. The try square has a blade, with parallel surfaces. The blade is fixed to the stock at, 90°., Try squares are made of hardened steel., Try squares are specified according to the length of the, blade i.e. 100 mm, 150 mm, 200 mm., Uses:, The try-square is used to:, – check the squareness (Fig 2), , – check the flatness (Fig 3), , 58, , Copyright Free Under CC BY Licence
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Elements of a file, Objectives: At the end of this lesson you shall be able to, • name the parts of a file, • state the material of a file., Methods of material cutting, The three methods of metal cutting are abrasion (Fig.1),, fusion (Fig 2) and incision (Fig 3), , Filling is a method for removing excess material from a, workpiece by using a file which acts as a cutting tool., Figure 4 shows how to hold a file. Files are available in, many shapes and sizes., , Tip or Point, the end opposite to tang, Face or side, The broad part of the file with teeth cut on its surface, Edge, The thin part of the file with a single row of parallel teeth, Heel, The portion of the broad part without teeth, Shoulder, the curved part of the file separating tang from the body, Tang, The narrow and thin part of a file which fits into the handle, Handle, The part fitted to the tang for holding the file, , Parts of a file (Fig 5), The parts of a file can be seen in figure 5, are, , Ferrule, A protective metal ring to prevent cracking of the handle., Materials, Generally files are made of high carbon or high grade cast, steel. The body portion is hardened and tempered. The, tang is however not hardened., , P&M : Fitter - Related Theory for Exercise 1.2.17, , Copyright Free Under CC BY Licence, , 59
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Cut of files, Objectives: At the end of this lesson you shall be able to, • name the different cuts of files, • state the uses of each type of cut., The teeth of all file are formed by cuts made on its face., Files have cuts of different types. Files with different cuts, have different uses., Types of cuts, , Rasp cut file (Fig 3), The rasp cut has individual, sharp, pointed teeth in a line,, and is useful for filing wood, leather and other soft materials., These files are available only in half round shape., , Basically there are four types., Single cut, Double cut, Rasp cut and Curved cut., Single cut file (Fig 1), A single cut file has rows of teeth cut in one direction across, its face. The teeth are at an angle of 600 to the centre line., It can cut chips as wide as the cut of the file. Files with this, cut are useful for filing soft metals like brass, aluminium,, bronze and copper., , Curved cut file (Fig 4), These files have deeper cutting action and are useful for, filing soft materials like - aluminium, tin, copper, and, plastic., Single cut files do not remove stock as fast double cut files,, but the surface finish obtained is much smoother., Double cut file (Fig 2), A double cut file has two rows of teeth cut diagonal to each, other. The first row of teeth is known as OVERCUT and they, are cut at an angle of 700 . The other cut, made diagonal to, this, is known as UPCUT, and is at an angle of 510 . This, removes stock faster than the single cut file., , The curved cut files are available only in a flat shape., The selection of a file with a particular type of, cut is based on the material to be filed. Single, cut files are used for filing soft materials. But, certain special files, for example, those used, for sharpening saws, are also of single cut., , 60, , P&M : Fitter - Related Theory for Exercise 1.2.17, , Copyright Free Under CC BY Licence
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File specifications and grades, Objectives: At the end of this lesson you shall be able to, • state how files are specified, • name the different grades of files, • state the application of each grade of file., Files are manufactured in different types and grades to meet the, various needs., Files are specified according to their length, grade, cut and, shape., , It may also be observed that the number of cutting, edges in rows of a file changes according to the, Length of a file., A smooth file is used to, remove small quantity of, material and to give a good, finish., , Length is the distance from the tip of a file to the heel., , File grades are determined by the spacing of the teeth., , A dead smooth file, is used to bring the, material to accurate, size with a high, degree of finish., , A rough file is used for removing, rapidly a larger quantity of metal., It is mostly used for trimming, the rough edges of soft metal, castings., , The most used grades of files are bastard,, second cut, smooth and dead smooth.These are, the the grades recommended by the bureau of, indian standards (BIS), , A bastard file is used in, cases where there is a heavy, reduction of material, , Different sizes of files with the same grade will have, varying sizes of teeth. In longer files, the teeth will be, coarser., The number of cutting edge in rows in each of the, above grades over a Length of 10mm as shown in, Table (1)., , A second cut file is used to, give a good finish on metals. It, is excellent to file hard metals., It is useful for bringing the jobs, close to the finishing size., TABLE (1), , Grade of files (Number of cuts over the length of 10mm), Length of file, , Rough, , Bastard, , Second cut, , Smooth, , Deadsmooth, , 150mm, , 8, , 13, , 17, , 24, , 33, , 200mm, , 7, , 11, , 16, , 22, , 31, , 250mm, , 6, , 10, , 15, , 20, , 30, , 300mm, , 5, , 9, , 14, , 19, , 28, , P&M : Fitter - Related Theory for Exercise 1.2.17, , Copyright Free Under CC BY Licence, , 61
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Production & Manufacturing, Fitter - Basic fitting, , Related Theory for Exercise 1.2.18, , Types of files, Objectives: At the end of this lesson you shall be able to, • identify the different shape of files(types), • state the uses of flat files, Hand files square, round, half round, triangular and knife-edge files, • state the correct shape of files for filing different profiles., For filing and finishing different profiles, files of, different shapes are used, The shape of files is stated by its cross section., Common files of different shapes: Flat file, Hand file,, Square file, Round file, Half round file, Triangular file and, Knife-edge file., Flat file (Fig 1 ), These files are of a rectangular cross section. The edges, along the width of these files are parallel up to two-thirds, of the length, and then they taper towards the point. The, faces are double cut, and the edges single cut. These, files are used for general purpose work. They are useful for, filing and finishing external and internal surfaces., , Round file: A round file is circular in its cross section. It, is used for enlarging the circular holes and filing profiles, with fillets. (Fig.4), , Hand file (Fig 2), These files are similar to the flat files in their cross section., The edges along the width are parallel throughout the length., The faces are double cut. One edge is single cut whereas, the other is safe edge. Because of the safe edge, they are, useful for filing surfaces which are at right angles to, surfaces already finished., , Flat files are general purpose files. They are, available in all grades. Hand files are particularly, useful for filling at right angles to a finished, surface., Square File: The square file is square in its cross section., It is used for filing square holes, internal square corners,, rectangular openings, keyways and splines. (Fig 3), , Half round file: A half round file is in the shape of a, segment of a circle. It is used for filing internal curved, surfaces. (Fig.5), , Knife edge file: A knife edge file has the cross section of, a sharp triangles. It is used for filing narrow grooves and, angles above 10o (Fig.7), The above files have one third of their lengths tapered., They are available both single and double cuts., , 62, , Copyright Free Under CC BY Licence
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Triangular file: A triangular file is of a triangular cross, section. It is used for filing corners and angles which are, more than 60o. (Fig.6), , Square, round, half-round and triangular files are available, in lengths of 100, 150, 200, 250, 300 and 400mm. These, files are made in bastard, second cut and smooth grades., , Needle files, Objectives: At the end of this lesson you shall be able to, • name the different shapes of needle files, • designate needle files as per BIS., Needle files are usually available in sets with assorted, shapes. These types of files are used for delicate, light, kinds of work. These files are available in bastard and, smooth grade., , Nomenclature of needle files. (Fig.2), , Shapes:The common shapes of needle files are shown in, figure 1. The shapes are round edge, flat edge, flat taper,, half round, triangular, square, round, knife, feather edge,, crossing, barret and marking. (Fig 1), , Length: These files are available in a nominal length of, 120mm to 180mm., Grades: The grades of cut may be identified by the cut, number as follows, - bastard - Cut 0., - smooth - Cut 2., Designation of needle files: The needle files are, designated by their names, - grade of cut, - nominal length, - BIS number, Example, A flat edge needle file with grade of cut bastard, having a, nominal length of 160mm shall be designated as flat edge, needle file bastard, 160 IS 3152, , P&M : Fitter - Related Theory for Exercise 1.2.18, , Copyright Free Under CC BY Licence, , 63
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Special files, Objectives: At the end of this lesson you shall be able to, • name the different types of special files, • state the uses of each type of special files., In addition to the common type of files, files are also, available in a variety of shapes for ‘special’ applications., These are as follows., Riffler files (Fig 1): These files are used for die-sinking,, engraving and in silversmith’s work. They are made in, different shapes and sizes and are made with standard, cuts of teeth., , Mill saw files (Fig 2): Mill saw files are usually flat and, have square or rounded edges. These are used for, sharpening teeth of wood-working saws, and are available, in single cut., , Tinker’s file (Fig 5): This file has a rectangular shape, with teeth only at the bottom face. A handle is provided on, the top. This file is used for finishing automobile bodies, after tinkering., , Rotary files (Fig 6): These files are available with a round, shank. They are driven by a special machine with a portable, motor and flexible shaft. These are used in diesinking and, mould-making work., , Crossing file (Fig 3): This file is used in the place of a half, round file. Each side of the file has different curves. It is, also known as ‘fish back’ file., , Barrette file (Fig 4): This file has a flat, triangular face, with teeth on the wide face only. It is used for finishing, sharp corners., , 64, , P&M : Fitter - Related Theory for Exercise 1.2.18, , Copyright Free Under CC BY Licence
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Machine files for hand filing machine (Fig 7): Machine, files are of double cut, having holes or projections to fix to, the holder of the filing machine. The length and shape will, vary according to the machine capacity. These files are, suitable for filing the inner and outer surfaces, and are, ideal for diesinking and other tool-room work., , Pinning of files, Objective: At the end of this lesson you shall be able to, • clean the files., During filing, sometimes the metal chips (filings) will clog, between the teeth of files. This is known as ‘pinning’ of, files., Files which are pinned will produce scratches on the, surface being filed, and also will not bite well., Pinning of the files is removed by using a file brush also, called a file card, (Fig 1) with either forward or backward, stroke., , For new files, use only soft metal strips (brass or copper), for cleaning. The sharp cutting edges of the files will wear, out quickly if a steel file card is used. When filing a, workpiece to a smooth finish more ‘pinning’ will take place, because the pitch and depth of the teeth are less., Application of chalk on the face of the file will help reduce, the penetration of the teeth and ‘pinning’., Filings which do not come out easily by the file card should, be taken out with a brass or copper strip. (Fig 2), , Clean the file frequently in order to remove the filings, embedded in the chalk powder., , Care and maintenance, Objective: At the end of this lesson you shall be able to, • write the care and maintenance of file., , • Do not use files having the blunt cutting edge, • Remember that files cut on the push stroke. Never, apply the pressure on the pull stroke, or you could, crush the file teeth, blunt them or cause them to break, off., , • Giving your files teeth a light brush with oil during long, storage., , • Normally do not apply any oil while filing., • Files should be stored separatelly so that their faces, cannot rub against each other or against other tools., , • Prevent from pinning., , P&M : Fitter - Related Theory for Exercise 1.2.18, , Copyright Free Under CC BY Licence, , 65
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Convexity of files, Objective: At the end of this lesson you shall be able to, • list the reasons for convexity on files., Most files have the faces slightly bellied lengthwise. This, is known as convexity of a file. This should not be confused, with the taper of a file. A flat file has faces which are convex, and it also tapers slightly in width and thickness., Purpose: If the file is parallel in thickness, all the teeth on, the surface of the work will cut. This would require more, downward pressure to make the file ‘bite’ and also more, forward pressure to make the file to cut., It is more difficult to control a file of uniform thickness., To produce a flat surface with a file of parallel thickness,, every stroke should be straight. But it is not possible due, to the see-saw action of the hand., If the file is made with parallel faces, while giving heat, treatment, one face may warp and become concave, and, the file will be useless for flat filing., Excessive chip removal at the front or rear workpiece edge, is prevented and filing of the flat surface is made easier, because of the convexity on the cutting faces. (Fig 1), , 66, , P&M : Fitter - Related Theory for Exercise 1.2.18, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.19, , Measurement of angles, Objectives: At the end of this lesson you shall be able to, • state the units and fractional units of angles, • express degrees, minutes and seconds using symbols., The unit of an angle, For angular measurements a complete circle is divided, into 360 equal parts. Each division is called a degree., (A half circle will have 180°) (Fig 1), , Subdivisions of an angle, , Examples for angular divisions, , For more precise angular measurements, one degree is, further divided into 60 equal parts. This division is one, MINUTE (‘). The minute is used to represent a fractional, part of a degree and is written as 30° 15’., , 1, , complete circle, , 360°, , 1/2, , circle, , 180°, , 1/4, , of a circle, , One minute is further divided into smaller units known as, seconds (“). There are 60 seconds in a minute., An angular measurement written in degrees, minutes and, seconds would read as 30° 15' 20"., , 90°, , (right angle), Sub divisions, , 1 degree or 1° = 60 mts or 60', 1 min or 1' = 60 secs or 60", , 67, , Copyright Free Under CC BY Licence
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Angular measuring instruments (Semi-precision), Objectives: At the end of this lesson you shall be able to, • state the names of semi-precision angular measuring instruments, • differentiate between bevel and universal bevel gauges, • state the features of bevel protractors., The most common instruments used to check angles are, the:, bevel or bevel gauge (Fig 1), , Universal bevel gauges : The universal bevel gauge has, an additional blade. This helps in measuring angles which, cannot be checked with an ordinary bevel gauge. (Fig 4), , universal bevel gauge (Fig 2), bevel protractor. (Fig 3), , Bevel protractor (Fig 3): The bevel protractor is a direct, angular measuring instrument, and has graduation marked, from 0° to 180°. Angles can be measured within an, accuracy of 1° using this instrument. (Fig 3), , Bevel gauges : The bevel gauges cannot measure angles, directly. They are, therefore, indirect angular measuring, instruments. The angles can be set and measured with, bevel protractors., , Combination set, Objectives: At the end of this lesson you shall be able to, • name the parts of a combination set, • state the uses of each attachment in a combination set, Combination sets can be used for different types of work,, like layout work, measurement and checking of angles., , Square Head, , The combination set (Fig 1) has a, , The square head has one measuring face at 900 and, another at 450 to the rule., , Protractor head, Square Head, Centre head, and a, Rule, , It is used to mark and check 900 and 450 angles. It can also, be used to set workpieces on the machines and measure, the depth of slots. (Fig 2,3 and 4), , (1), (2), (3), (4), , Protractor Head, The protractor head can be rotated and set to any required, angle., , Centre Head, This along with the rule is used for locating the centre of, cylindrical jobs. (Fig 5), , For ensuring accurate results, the combination set, The protractor head is used for marking and measuring, should be cleaned well after use and should not be, angles within an accuracy of 10 . The spirit level attached to, mixed with cutting tools, either while using or storing., this is useful for setting jobs in a horizontal plane. (Fig.6), 68, P&M : Fitter - Related Theory for Exercise 1.2.19, , Copyright Free Under CC BY Licence
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Measuring standards (English & metric), Objective: At the end of this lesson you shall be able to, • describe the measuring standards of english and metric units., Necessity, All physical quantities are to be measured in terms of, standard quantities., Unit, A unit is defined as a standard or fixed quantity of one, kind used to measure other quantities of the same kind., Classification, Fundamental units and derived units are the two, classifications., Fundamental units, Units of basic quantities of length, mass and time., Derived units, Units which are derived from basic units and bear a constant, relationship with the fundamental units., , Ex : Area, Volume, Pressure, Force, etc., System of units, F.P.S. system is the British system in which the basic, units of length, mass and time are foot, pound and second, respectively., C.G.S. system is the metric system in which the basic, units of length, mass and time are centimetre, gram and, second respectively., M.K.S system is another metric system in which the basic, units of length, mass and time are metre, kilogram and, second respectively., S.I. units is referred to as Systems International units which, is again of metric and the basic units, their names and, symbols are Listed in table - 1, , P&M : Fitter - Related Theory for Exercise 1.2.19, , Copyright Free Under CC BY Licence, , 69
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Table 1, Basic Quantity, , Metric Unit, Name, , Symbol, , British unit, Name, , Symbol, , Length, , Metre, , m, , Foot, , F, , Mass, , Kilogram, , kg, , Pound, , P, , Time, , Second, , S, , Second, , S, , Current, , Ampere, , A, , Ampere, , A, , Temperature, , Kelvin, , K, , Farenheit, , Fo, , Light intensity, , Candela, , Cd, , Candela, , Cd, , Fundamental units and derived units are the, two classification of units., Length, mass and time are the fundamental, units in all the systems (ie) F.P.S, C.G.S, M.K.S, and S.I systems., , 70, , P&M : Fitter - Related Theory for Exercise 1.2.19, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.20, , Surface gauges, Objectives: At the end of this lesson you shall be able to, • state the uses of surface gauges, • name the types of surface gauges, • state the advantages of universal surface gauges., • state care and maintenance of surface gauges, The surface gauge is one of the most common marking, tools used for:, scribing lines parallel to a datum surface (Fig.1), , Setting jobs on machines parallel to a datum surface, (Fig.2), , Universal surface gauge (Fig 5), , Checking the height and parallelism of jobs, setting jobs, concentric to the machine spindle. (Fig 3), , This has the following additional features: The spindle can, be set to any position. Fine adjustment can be made, quickly. Can also be used on cylindrical surfaces., , Types of surface gauges, Surface gauges/scribing blocks are of two types, fixed and, universal., Suface gauge - fixed type (Fig 4), The fixed Type of surface gauge consists of a heavy flat, base and a spindle, fixed upright, to which a scriber is, attached with a snug and a clamp nut., 71, , Copyright Free Under CC BY Licence
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Parallel lines can be scribed from any datum edge with the, help of guide pins. (Fig 6), , Rocker arm, The rocker arm is attached to the base along with a spring, and a fine adjustment screw. This is used for fine, adjustments., Spindle, The spindle is attached to the rocker arm., Scriber, The scriber can be clamped in any position on the spindle, with the help of a snug and a clamping nut., , Parts and functions of a Universal Surface Gauge, , Care and maintenance, , Base, , • Clean before and after the use, , The base is made of steel or cast iron with a 'V groove at the, bottom. The 'V' groove helps to seat on circular work.The, guide-pins, fitted in the base, are helpful for scribing lines, from any datum edge., , • Apply thin layer of oil to the bottom of the surface, base before using for marking., , • Sharpen the Scriber if necessary., • Do not exert more pressure while marking, , 72, , P&M : Fitter - Related Theory for Exercise 1.2.20, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.21, , Cold Chisel, Objectives: At the end of this lesson you shall be able to, • list the uses of a cold chisel, • name the parts of a cold chisel, • state the different types of chisels, • specify the chisel, The cold chisel is a hand cutting tool used by fitters for, chipping and cutting off operations. (Fig 1), , − Diamond point chisel, − Web chisel, Flat chisels (Fig.3a): They are used to remove metal from, large flat surfaces and chip-off excess metal of welded, joints and castings., Cross-cut or cape chisels (Fig.3b): These are used for, cutting key ways, grooves and slots., , Chipping is an operation of removing excess metal with, the help of a chisel and hammer. Chipped surfaces being, rough, they should be finished by filing., Parts of a Chisel (Fig 2): A chisel has the following parts., , Half-round nose chisels (Fig 4): They are used for cutting, curved grooves (oil grooves)., , Head, body, point or cutting edge., Chisels are made from high carbon steel or chrome, vanadium steel. The cross-section of chisels is usually, hexagonal or octagonal. The cutting edge is hardened and, tempered., Common types of chisels: There are five common types, of chisels., − Flat chisel, − Cross-cut chisel, − Half-round nose chisel, , Diamond point chisels (Fig 5): These are used for, squaring materials at the corners, joints., , 73, , Copyright Free Under CC BY Licence
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Web chisels/ punching chisels (Fig 6): These chisels, are used for separating metals after chain drilling., , − width of the cutting edge, , Chisels are specified according to their, , − type, , − length, , − cross-section of the body., , Angles of chisels, Objectives: At the end of this lesson you shall be able to, • select the point angles of chisels for different materials, • state the effect of rake and clearance angles, • brief the care and maintenance of chisels., Clearance angle: Clearance angle is the angle between, Point angles and materials: The correct point/cutting, the, bottom face of the point and the tangent to the work, angle of the chisel depends on the material to be chipped., surface, originating at the cutting edge. (Fig 2), Sharp angles are given for soft materials, and wide angles, for hard materials., The correct point and angle of inclination generate the, correct rake and clearance angles. (Fig 1), , Rake angle: Rake angle is the angle between the top, face of the cutting point, and normal (90°) to the work, surface at the cutting edge. (Fig 2), , 74, , If the clearance angle is too low or zero, the rake angle, increases. The cutting edge cannot penetrate into the work., The chisel will slip. (Fig 3), , If the clearance angle is too great, the rake angle reduces., The cutting edge digs in and the cut will become deeper, and deeper. (Fig 4) The correct point angle and angle of, inclination for different materials for chipping is given in, Table 1., , P&M : Fitter - Related Theory for Exercise 1.2.21, , Copyright Free Under CC BY Licence
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Crowning: A slight curvature is ground called “Crowning”, to the cutting edge of the chisel, to prevent digging of, corners, which leads to breakage of chisel point., “Crowning” allows the chisel to move freely along a straight, line while chipping., Table 1, Material, to be cut, , Point angle, , Angle, inclination, , High Carbon Steel, , 65°, , 39.5°, , Cast iron, , 60°, , 37°, , Mild steel, , 55°, , 34.5°, , Brass, , 50°, , 32°, , Copper, , 45°, , 29.5°, , Aluminium, , 30°, , 22°, , Care & maintenance, •, , Sharpen the chisel before use., , •, , Apply oil to avoid rust., , •, , Don't use the mushroom head chisel., , •, , Use safety goggles while chipping., , •, , While chipping., , •, , No greasy subject on the head of the chisel., , Ordinary depth gauge, Objectives: At the end of this lesson you shall be able to, • state the uses of ordinary depth gauge, • name the parts of depth gauge., Ordinary depth gauge, Ordinary depth gauge is semi precision instrument used, for measuring of depth of recesses, slots and steps., Parts of ordinary depth gauge, 1, , Graduated beam, , 2, , Clamping screw, , 3, , Scale, , 4, , Base, , Available in the ranges of 0-200 mm. Ordinary depth gauge, is used to measure an accuracy of 0.5 mm., , P&M : Fitter - Related Theory for Exercise 1.2.21, , Copyright Free Under CC BY Licence, , 75
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.22, , Sharpening of chisels, Objective: At the end of this lesson you shall be able to, • state the procedure for resharpening the cold chisels on pedestal grinding machines., Chisels will become blunt due to use. For efficiency in, chipping. the chisels are to be re-sharpened regularly., Chisels are sharpened on grinding machines. (Fig 1), , Inspect the tool rest, If there is too much of gap between the tool-rest and the, wheel, adjust it, and position it as close to the wheel as, possible. (Fig.3), , Ensure that there is sufficient coolant in the container., While grinding, rest the body of the chisel on the tool-rest, (A) and allow the point to touch the wheel. (Fig. 4), , After re-grinding many times, the cutting edges become, too thick. Such chisels are unsuitable for resharpening., They should be forged and brought to shape before grinding., (Fig 2), , Before commencing grinding, the following procedure should, be observed., Ensure the wheel guards are in place, and are, securely fastened., , Rock the point slightly on both sides in an arc (B) to provide, a slight convexity at the cutting edge. This will help to avoid, digging in the sides while chipping. (Fig 4), , Inspect the condition of the grinding wheel for, breakage and cracks., , Keep moving the chisel across the face (C) of to Prevent, formation of curves and grooves at the cutting edge., , Wear safety goggles., , Dip the chisel frequently in the coolant to avoid overheating., Overheating will draw the temper of the chisel., , When switching on the grinding machine, stand, aside untill the wheel reaches the operating, speed., 76, , Copyright Free Under CC BY Licence
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If the chisel-head is mushroomed, it should be cleaned by, grinding. (Fig 5), , Use only the front of the grinding wheel. (Fig 4) Do not grind, on the sides. (Fig 6), Use goggles while using a grinder, Any damage to the grinding wheel, if noticed, should be reported to the instructor., Do not use cotton waste or other material for, holding the chisel while grinding., , P&M : Fitter - Related Theory for Exercise 1.2.22, , Copyright Free Under CC BY Licence, , 77
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.23, , Marking media, Objectives: At the end of this lesson you shall be able to, • state the purpose of marking media, • name the common types of marking media, • select the correct marking medium for different applications., Purpose of marking media, , Copper sulphated, , In marking off/Layout, the surface of the job/workpiece is, coated with a medium to show the marked lines clear and, visible. To get clear and thin lines, the best layout medium, is to be selected., , The solution is prepared by mixing copper sulphate water, and a few drops of nitric acid. The copper sulphate is used, on filed or machine-finished surfaces. Copper sulphate, sticks to the finished surfaces well., , Different marking media, , Copper sulphate needs to be handled carfully as it is, poisonous. Copper sulphate coating should be dried before, commencing marking, as otherwise, the solution may, , The different marking media are Whitewash, Marking blue,, Prussian Blue, Copper Sulphate and Cellulose Lacquer., Whitewash, Whitewash is prepared in many ways., Chalk powder mixed with water, Chalk mixed with methylated spirit, White lead powder mixed with turpentine, Whitewash is applied to rough forgings andcastings with, oxidised surface. (Fig 1), Whitewash is not recommended for workpieces of high, accuracy., Marking blue, , stick on the instruments used for marking., , A Chemical dye, blue based colour mixed with methylated, spirit used for marking on workpieces which are reasonably, machined surface., , Cellulose lacquer: This is a commercially available, marking medium. It is made in different colours and dries, very quickly., , Prussian blue, This is used on filed or machine-finished surfaces. This will, give very clear lines but takes more time for drying than the, other marking media. (Fig 2), , The selection of marking medium for a particular, job depends on the surface finish and the, accuracy of the workpiece., In present days, marking media used are readily, available in aerosol container, which can be, applied by spraying on to any surface, which, needs marking., Readymade solutions of marking dye/ink which, are quick drying and thin layer to mark precise, dimensions and clear visible lines. Also, permanent marker pens are available in, different. colours, which are quick drying and, used for smaller workpieces of metal, wood, and plastics., , 78, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.24, , Surface plates, Objectives: At the end of this lesson you shall be able to, • state the necessity of surface plate, • state the material of surface plate, • state the specification of surface plate., Surface plates - their necessity, When accurate dimensional features are to be marked, it, is essential to have a datum plane with a perfectly flat, surface. Marking using datum surfaces which are not, perfectly flat will result in dimensional inaccuracies. (Fig.1), The most widely used datum surfaces in machine shop, work are the surface plates and marking tables., , Other materials used, Granite is also used for manufacturing surface plates., Granite is a dense and stable material. Surface plates, made of granite retain their accuracy, even if the surface, is scratched. Burrs are not formed on these surfaces., Classification and uses, Materials and construction, Surface plates are generally made of good quality cast, iron which are stress-relieved to prevent distortion., The work-surface is machined and scraped. The underside, is heavily ribbed to provide rigidity. (Fig 2), , Surface plates used for machine shop work are available, in three grades - Grades 1, 2 and 3. The grade 1 surface, plate is more acceptable than the other two grades., Specifications, Cast iron surface plates are designated by their length,, breadth, grade and the Indian Standard number., Example, Cast iron surface plate 2000 x 1000 Gr1. I.S. 2285., Care & maintenance, •, , Clean before and after use., , •, , Do not keep job on the surface plate., , •, , Don't keep any cutting tool on the table., , For the purpose of steadiness and convenience in levelling,, a three point suspension is given. (Fig 3), Smaller surface plates are placed on benches while the, larger surface plates are placed on stands., , 79, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.25, , Angle plates, Objectives: At the end of the lesson you shall be able to, • state the constructional features of different types of angle plates, • name the types of angle plates, • state the uses of different types of angle plates, • state the grades of angle plates., • specify angle plates., Constructional features, Angle plates have two plane surfaces, machined perfectly, flat and at right angles. Generally these are made of closely, grained cast iron or steel. The edges and ends are also, machined square. They have ribs on the unmachined part, for good rigidity and to prevent distortion., Types of angle plates, Plain solid angle plate (Fig 1), , Swivel type angle plate (Fig 5), , Among the three types of angle plates normally used, the, plain solid angle plate is the most common. It has the, two plane surfaces perfectly machined at 90° to each other., Such angle plates are suitable for supporting work-pieces, during layout work. They are comparatively smaller in, size., Slotted type angle plate (Fig 2), The two plane surfaces of this type of angle plate have, slots milled. It is comparatively bigger in size than the, plain solid angle plate., The slots are machined on the top plane surfaces for, accommodating clamping bolts. This type of angle plate, can be tilted 90° along with the work for marking or, machining. (Figs 3 and 4), 80, , Copyright Free Under CC BY Licence
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This is adjustable so that the two surfaces can be kept at, an angle. The two machined surfaces are on two separate, pieces which are assembled. Graduations are marked on, one to indicate the angle of tilt with respect to the other., When both zeros coincide, the two plane surfaces are at, 90° to each other. A bolt and nut are provided for locking in, position., , Sizes, , Box angle plate (Fig 6), , a) Size 6 Grade 1, , They have applications similar to those of other angle, plates. After setting, the work can be turned over with the, box enabling further marking out or machining. This is a, significant advantage. This has all the faces machined, square to each other., , Angle plates are available in different sizes. The sizes are, indicated by numbers. Table 1 gives the number of the, sizes and the corresponding size proportions of the angle, plates., Specification of angle plates, Box plate will be designated as - box angle plate 6 Gr, 1 IS 623., b) Size 2 - Grade 2 angle plate will be designated as, Angle plate 2 Gr 2 I.S 623., TABLE 1, , Grades, , Size No., , L, , B, , H, , 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, , 125, 175, 250, 350, 450, 600, 700, 600, 1500, 2800, , 75, 100, 150, 200, 300, 400, 420, 600, 900, 900, , 100, 125, 175, 250, 350, 450, 700, 1000, 1500, 2200, , Grade 2 only, , Angle plates are available in two grades - Grade 1 and, Grade 2. The Grade 1 angle plates are more accurate and, are used for very accurate tool room type of work. The, Grade 2 angle plates are used for general machine shop, work. In addition to the above two grades of angle plates,, precision angle plates are also available for inspection, work., , Care & Maintenance, − Clean before and after use., − Apply oil after the use., , Parallel blocks, Objectives: At the end of this lesson you shall be able to, • name the types of parallels, • state the constructional features of parallel blocks, • specify parallel blocks as per BIS recommended, • state the uses of parallel blocks., Parallel blocks of different types are used for setting, workpieces for machining. The commonly used are of, two types., − Solid Parallels, − Adjustable Parallels, Solid parallels (Solid parallel blocks) (Fig 1), This is the type of parallel which is very much used in, machine shop work. They are made of steel pieces of, rectangular cross section, and are available in different, lengths and cross sectional sizes., P&M : Fitter - Related Theory for Exercise 1.2.25, , Copyright Free Under CC BY Licence, , 81
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They are hardened and ground, and, sometimes, finished, by lapping., Parallels are machined to close limits, and are perfectly, flat, square, and parallel throughout the length. These are, made in pairs of identical dimensions., Grades, Parallels are made in two grades - Grade A and Grade B., Grade A is meant for fine toolroom type of work, and Grade, B for general machine shop work., , Designation of parallels, Parallels are designated by the type, grade (for solid, parallels only) size, and the number of the standard. Fig 4, Examples, Solid parallel A5 x 10 x 100 IS: 4241, Adjustable parallel 10 x 13 IS:4241, , Adjustable parallels (Fig 2), These consist of two tapered blocks sliding one over the, other in a tongue and groove assembly. These types of, parallels can be adjusted and set to different heights., , Table 1, Sizes of solid parallels, Grade, , Uses, , A, A, A, A, A, A, A, , Solid and adjustable parallels are used for parallel setting, of workpieces while machining. They are also useful for, raising the workpieces held in vices or machine tables to, provide better observation of the machining process., (Fig 3), , Table 2, Range and size of Adjustable Parallels, , Parallels are made in pairs and should be used, in matching pairs to ensure accuracy in set-up., Care and maintenance, − Clean before and after the use., − Apply oil after use, − Do not use as a hammer., Sizes of parallels, , &, &, &, &, &, &, &, , B, B, B, B, B, B, B, B, B, , Size T.W.L., 5 x 10 x 100, 10 x 20 x 150, 15 x 25 x 150, 20 x 35 x 200, 25 x 45 x 250, 30 x 60 x 250, 35 x 70 x 300, 40 x 80 x 350, 50 x 100 x 400, , Height Range, 10 - 13, 13 - 16, 16 - 20, 20 - 25, 25 - 30, 30 - 40, 40 - 50, , These are given in TABLE 1 and TABLE 2., 82, , P&M : Fitter - Related Theory for Exercise 1.2.25, , Copyright Free Under CC BY Licence, , Length, 40, 50, 60, 65, 70, 85, 100
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.26-30, , Physical and mechanical properties of metals, Objectives: At the end of this lesson you shall be able to, • name the different physical and mechanical properties of materials, • state the characteristics of the mechanical properties of metals., Properties of metals, Metals have different properties. Depending on the type of, application, different metals are selected., Physical properties of metals, •, , Colour, , •, , Weight/Specific gravity, , •, , Structure, , •, , Conductivity, , •, , Magnetic property, , •, , Fusibility, , Almost all ferrous metals, excepting some types of, stainless steel, can be attracted by a magnet and all, non-ferrous metals and their alloys will not be attracted by, a magnet., Fusibility (Fig 3), It is the property possessed by a metal by virtue of which, it melts when heat is applied. Many materials are subject, to the transformation in shape (i.e.) from solid to liquid at, different temperatures. Tin has a low melting temperature, (232ºC)and tungsten melts at a high temperature, (3370ºC)., , Colour, Different metals have different colours. For example, copper, is of a distinctive red colour. Mild steel is of a blue/black, sheen., Weight, Metals differ based on their weight. A metal, like aluminium,, weighs lighter (specific gravity 2.8) than many others, and, a metal, like lead, is heavy (specific gravity 9)., Structure (Figs 1 and 2), , Specific gravity, It is the ratio between the weight of the metal and the, weight of equal volume of water., Mechanical properties, The mechanical properties of a metal are, •, , ductility, , •, , malleability, , Generally metals can also be differentiated by their internal, microstructure. Metals like wrought iron and aluminium, will have a fibrous structure, and metals like cast iron and, bronze will have a granular structure., , •, , hardness, , •, , brittleness, , •, , toughness, , Conductivity, , •, , tenacity, , Thermal conductivity and electrical conductivity are the, measure of the ability of a material to conduct heat and, electricity. Conductivity will vary from metal to metal., Copper and aluminium are good conductors of heat and, electricity., , •, , elasticity, , Magnetic property, A metal is said to possess magnetic property, if it is, attracted by a magnet., , Ductility (Fig 4), A metal is said to be ductile when it may be drawn out in, tension without rupture. Wire-drawing depends upon, ductility for its successful operation. A ductile metal must, be both strong and plastic. Copper and aluminium are, good examples of ductile metals., , 83, , Copyright Free Under CC BY Licence
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Malleability (Figs 5 and 6), Toughness (Fig 9), , Toughness is the property of a metal to withstand shock, or impact. Toughness is the property opposite to, brittleness. Wrought iron is an example of a tough metal., Malleability is the property of permanently extending in all, directions without rupture by hammering, rolling etc. to, change its size and shape. Lead is a very malleable metal., , Tenacity (Fig 10), , Hardness (Fig 7), , Hardness is a measure of a metal's ability to withstand, scratching, wear, abrasion and penetration., Brittleness (Fig 8), Brittleness is the property of a metal which permits no, permanent distortion before breaking. Cast iron is an, example of a brittle metal, and it will break rather than, bend under shock or impact., , 84, , Tenacity of a metal is its ability to resist the effect of tensile, forces without rupture. Mild steel, wrought iron and copper, are examples of tenacious metals., , P&M : Fitter - Related Theory for Exercise 1.2.26 - 1.2.30, , Copyright Free Under CC BY Licence
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Elasticity (Fig 11), , Elasticity of a metal is its power of returning to its original, shape after the applied force is released. Properly, heat-treated spring is a good example of elasticity., Specific gravity, It is the ratio between the weight of the metal and the, weight of equal volume of water., , P&M : Fitter - Related Theory for Exercise 1.2.26 - 1.2.30, , Copyright Free Under CC BY Licence, , 85
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.31, , Power hacksaw, Objectives: At the end of the lesson you shall be able to, • state the features of a power hacksaw, • select the correct blade for different jobs, • state the features of a power hacksaw blade, • state the features of work-holding and supporting devices, • name the parts of a power hacksaw, • state the method of fixing power saw blades., Cut off saws are used to cut metal stock roughly to the, required length. The commonly used cut- off saw in small, scale industries is a POWER SAW., Features, The power saw works like a hand hacksaw, and has an, arrangement for cutting during the movement in one, direction and releasing pressure on the non-cutting stroke., The rotary motion of the motor is coverted into linear motion, by a crank mechanism. (Fig 1), , Power hacksaw blades, The saw blades are selected, depending on the machine, and the type of work on hand. The blades are made of, H.S Steel and are fully hardened., For different materials, blades of different pitches are used, (number of teeth per 25mm length). (Fig 3), , As a general rule, the softer the material, the lesser is the, number of teeth, per length of 25 mm., Teeth with a large pitch can accommodate large chips, (Fig 4), , The required cutting pressure is obtained hydraulically or, by an adjustable weight., During the non-cutting motion the blade will be lifted away, from the work., A clamping device/vice holds the work firmly., Power saw: This is most commonly used metal cutting, saw. (Fig.2), , Blades are available with varying coarsenses i.e between, 4 to 14 teeth per inch length., Coarse pitch blades are also used while cutting large, sections of stock, as this will help in greater chip clearance, and increased penetration., For cutting hard material (example - tool steel), and thin, material, a 14 T.P.I blade is recommended., For general purpose sawing, a 10 TPI blade will be useful., While selecting blades, make sure atleast two, teeth of the blade will be in contact with the, work at all times., , 86, , Copyright Free Under CC BY Licence
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What will happen if less than two teeth are in contact with, the work?, The work can be caught in the tooth gullet, and cause, breakage to the blade. (Fig 5), , Clamping arrangement (Fig 8), Power saws are provided with clamping devices similar to, those in machine vices, and the work can be gripped by, using the crank handle., , Blade clearance (Fig 6), In order to avoid jamming of the teeth and to provide for, chip clearance, the teeth of the saw blades are offset or, waved., , When a number of pieces of the same size are to be cut, an adjustable stop is used., Long bars are supported, and the level maintained by the, use of adjustable floor stands. (Fig 9), , Fixing blades (Fig 10), The blades are mounted on frames using screws., The teeth of the blade should point towards correct, directions. (Depending on the type of machine the blade, either cuts on the forward or on the return stroke)., It is necessary to follow the directions given by the, manufacturer as indicated in the frame., Specification of power hacksaw blades (Fig 7), , Tension the blade using the tensioning device., , While specifying power hacksaw blades, it is necessary, to state, - The length (the distance between centre of holes)., - The width, - The thickness and, - The teeth pitch., P&M : Fitter - Related Theory for Exercise 1.2.31, , Copyright Free Under CC BY Licence, , 87
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.32, , Metal-cutting saws, Objectives: At the end of this lesson you shall be able to, • name the common types of metal-cutting saws, • state the advantages of a horizontal band-saw, • state the features of different types of cutting saws, • state the specific use of a contour-saw., • state the precautions to be observed while machine sawing., Metal-cutting saws of different types are used in industries., The most commonly used are the:, , Speed variation is obtained through the stepped pulleys on, the motor., , - power saw, , The roller-guide brackets provide the rigidity for the blade in, the cutting area and also prevent wandering of the blade, while cutting., , - horizontal band-saw, - circular saw, , The blade tension is mainatained by using the adjusting, handle. provided for this purpose., , - contour band-saw., Power saw (Fig 1), This is the most commonly used metal-cutting saw and, discussed in related theory for Ex: 1.2.31., , A vice is provided for holding the metal stocks. The vice is, adjustable for angular cutting., This machine has the advantage of continuous cutting, ability, and is much faster than a power saw. It may be, noted that a power saw cuts only in every alternate stroke., Cirucular saw (Fig 3), This type of cutting machine is used when cutting materials, have a large cross-section. The circular saw has a, continuous cutting action and is economical in production, work where heavy section metals are used., , Horizontal band-saw (Fig 2), This has a saw frame on which a motor is fitted., There are two pulley wheels on which an endless bandsaw, passes., , Contour saw (Fig 4), In this, a metal band saw blade is used, and the contour, saw has a continuous cutting motion. (Fig 5), These machines are very much used for cutting metals to, different profiles. (Fig 6), Different speeds can be obtained while cutting, with the, help of variable speed pulleys., For repairing broken countour saw blades, these machines, are fitted with a shear for trimming the blade ends, a buttwelding machine for joining the ends and the small grinder, to finish the welded joint., , 88, , Copyright Free Under CC BY Licence
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Ensure that the work does not protrude into the gangways., The table can be tilted to any angle for angular cutting., , When sawing thin pieces, hold the material flat in the vice, to prevent the saw teeth from breaking., , The blade passes through a guide which prevents the, blades from wandering and keeps it rigidly., , Ensure a cutting fluid is used always., , These machines are widely used for tool-room work, and, not as a machine for cutting raw material stock., Precautions to be observed while machine sawing, In order to work safely and efficiently, certain precautions, are to be observed., While taking measurements of the work for setting, always, stop the machine., Projecting ends of the work should be well guarded, so that, safety may be provided to others., , Avoid giving excessive cutting pressure, because this can, cause breakage to the blade, and cut work out of square., When several pieces of the same length are to be cut, use, a stop gauge., When holding short workpieces in a vice, be sure to place, a short piece of the same thickness in the opposite end., This will prevent the vice from twisting when it is tightened., Lubricate the machines on the indicated points using oil, can, oil gun or grease gun as specified by the machine, manufacturer., , P&M : Fitter - Related Theory for Exercise 1.2.32, , Copyright Free Under CC BY Licence, , 89
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.33, , Outside micrometer, Objectives: At the end of this lesson you shall be able to, • name the parts of an outside micrometer, • state the functions of the main parts of an outside micrometer., A micrometer is a precision instrument used to measure, a job, generally within an accuracy of 0.01 mm., Micrometers used to take the outside measurements are, known as outside micrometers. (Fig 1), The parts of a micrometer are listed here., , Spindle, One end of the spindle is the measuring face. The other, end is threaded and passes through a nut. The threaded, mechanism allows for the forward and backward movement, of the spindle., Anvil, , Frame, The frame is made of drop-forged steel or malleable cast, iron. All other parts of the micrometer are attached to this., Barrel/Sleeve, , The anvil is one of the measuring faces which is fitted on, the micrometer frame. It is made of alloy steel and finished, to a perfectly flat surface., Spindle lock nut, , The barrel or sleeve is fixed to the frame. The datum line, and graduations are marked on this., Thimble, , The spindle lock nut is used to lock the spindle at a desired, position., Ratchet stop, , On the bevelled surface of the thimble also, the graduation, is marked. The spindle is attached to this., , The ratchet stop ensures a uniform pressure between the, measuring surfaces., , Graduations of metric outside micrometer, Objectives: At the end of this lesson you shall be able to, • state the principle of a micrometer, • determine the least count of an outside micrometer., Working principle, , Graduations (Fig 1), , The micrometer works on the principle of screw and nut., The longitudinal movement of the spindle during one rotation, is equal to the pitch of the screw. The movement of the, spindle to the distance of the pitch or its fractions can be, accurately measured on the barrel and thimble., , In metric micrometers the pitch of the spindle thread is, 0.5 mm., Thereby, in one rotation of the thimble, the spindle, advances by 0.5 mm., , 90, , Copyright Free Under CC BY Licence
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On the barrel a 25 mm long datum line is marked. This, line is further graduated to millimetres and half millimetres, (i.e. 1 mm & 0.5 mm). The graduations are numbered as, 0, 5, 10, 15, 20 & 25 mm., The circumference of the bevel edge of the thimble is, graduated into 50 divisions and marked 0-5-10-15 ......., 45-50 in a clockwise direction., , The distance moved by the spindle during one rotation of, the thimble is 0.5 mm., Movement of one division of the thimble = 0.5 x 1/50, = 0.01 mm, Accuracy or least count of a metric outside, micrometer is 0.01 mm., , Reading dimensions with outside micrometer, Objectives: At the end of this lesson you shall be able to, • select the required range of a micrometer, • read micrometer measurements., Ranges of outside micrometer, Outside micrometers are available in ranges of 0 to 25, mm, 25 to 50 mm, 50 to 75 mm, 75 to 100 mm, 100 to, 125 mm and 125 to 150 mm., For all ranges of micrometers, the graduations marked on, the barrel is only 0-25 mm. (Fig 1), , First note the minimum range of the outside micrometer., While measuring with a 50 to 75 mm micrometer, note it, as 50 mm., Then read the barrel graduations. Read the value of the, visible lines on the left of the thimble edge., Reading micrometer measurements, How to read a measurement with an outside micrometer?, (Fig 2), , 13.00 mm (Main divison reading on barral), + 00.50 mm (Sub division reading on barral), 13.50 mm (Main division + sub - division value), Next read the thimble graduations., , P&M : Fitter - Related Theory for Exercise 1.2.33, , Copyright Free Under CC BY Licence, , 91
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Read the thimble graduations in line with the barrel datum, line, 13th div. (Fig 3), , Multiply this value with 0.01 mm (least count)., 13 x 0.01 mm = 0.13 mm., Add, Minimum range, , 50.00 mm, , Barrel reading, , 13.50 mm, , Thimble reading, , 00.13 mm, , Total, , 63.63 mm, , The micrometer reading is 63.63 mm., , Constructional features of outside micrometer, Objectives: At the end of this lesson you shall be able to, • name the internal parts of a micrometer, • state the functions of the various parts of a micrometer, • state the precautions to be observed while dismantling and assembling micrometers., In order to dismantle and carry out cleaning or adjustment, of a micrometer, it is essential to know the functions of its, various parts. (Fig 1), , Ratchet stop (Fig 2), This is a device fitted on micrometers to ensure uniform, pressure between the measuring face of the micrometer, while measuring., , The ratchet stop will slip beyond certain pressure, thus, preventing further advancement of the spindle when, excessive pressure is used., This is mounted on the thimble of the micrometer, and it, connects with the spindle when assembled., 92, , A special spanner is provided along with the micrometer for, fixing and removing the ratchet stop. (Fig 3), , Thimble, The thimble has a hollow taper (Fig 4) to match with the, taper nose fitted on the spindle., , P&M : Fitter - Related Theory for Exercise 1.2.33, , Copyright Free Under CC BY Licence
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Spindle, One end of the spindle forms the measuring face. The other, end of the spindle is threaded, the tapered nose is fitted on, it. (Fig 5), , The locking device provided on the spindle is to arrest the, movement of the spindle after taking the measurement., Preacautions while dismantilng micrometers, Avoid touching the measuring faces with bare fingers as, it might cause rusting., , The taper nose is very accurately finished for axial alignment, and it also permits postioning of the thimble in any required, place during the adjustment of zero error., The spindle passes through a split internal thread (Fig 6), which forms part of the barrel. The outer portion of this split, internal thread has tapered external threads. A taper, threaded nut is fitted on this., Tightening and loosening of this nut enables the spilt, internal thread to close or open. This permits the wear, adjustmet. in the mating threads., , Protect the the components of the micrometer free from, dust while dismantling and assembling., Use carbon tetrachloride for cleaning the parts after, dismantling., While assembling - apply a few drops of thin oil., Do not use metallic surface for placing the parts after, dismantling. An enamelled tray is preferable., Apply a thin coating of oil when placing the micrometer, back after the adjustment., Avoid frequent dismatling and assembling., , A special spanner is provided for this purpose. (Fig 7), , Inside micrometer, Objectives : At the end of this lesson you shall be able to, • list the purposes of an inside micrometer, • identify the parts of an inside micrometer, • state the safety precautions to be followed while using an inside micrometer., An inside micrometer is a precision measuring instrument, which measures with an accuracy of 0.01mm., , To measure the distance between internal parallel surfaces, like slots (Fig 2), , Purpose, , Parts (Fig 3), , An inside micrometer is used to measure the diameter of, holes. (Fig 1), , The following are the parts of an inside micrometer, , P&M : Fitter - Related Theory for Exercise 1.2.33, , Copyright Free Under CC BY Licence, , 93
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Micrometer head: It consists a sleeve, a thimble, an, anvil and locking screw for extension rods., Extension rod: This is fitted in the hole provided in the, barrel of the micrometer head. It provides another, measuring surface. It is available in different sizes., Locking Screw It is used to lock the extension rods., Handle It is fitted in the threaded hole provided in the, micrometer head. It is used to hold the micrometer, assembly while measuring deep bores., Spacing collar It is added to the extension rod for, additional length. It is available in different sizes., The range of inside micrometer, Using the different sizes of extension rods and spacing, collars the following ranges of measurement can be taken, 25-50mm, 50-200mm, 50-300mm, 200-500mm,2001000mm, Inside micrometer, Ranges of extension rod for (50 - 200mm) Inside, micrometer, Checking parallelism of surfaces of deep bores, , 94, , P&M : Fitter - Related Theory for Exercise 1.2.33, , Copyright Free Under CC BY Licence
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An extended handle can be used while measuring deep, bores. (Fig 4) for checking the parallelism of surfaces of, the bore., Find out the readings at 2 or 3 places i.e. one reading at, , Precautions, Ensure that the extension rod/spacing collar are fitted, correctly., Check the ‘O” setting of the inside micrometer with an, outside micrometer., Ensure that the measuring faces are perpendicular to the, axis, and the handle parallel to the axis of the above., When measuring bores the micrometer must be set for, the largest value. While measuring between flat surfaces,, the micrometer should be set for the smallest value., (Fig 5), Ensure that the wall surfaces of the bore are free from, burrs, oil etc. before using an inside micrometer. Set the, inside micrometer in the bore to the correct FEEL. Do not, drag or force the inside micrometer in the bore., , the top, another reading at the middle and the third reading, at the bottom of the bore. If all the three readings are the, same, then the surfaces of the bore are parallel. Any, variation in the readings shows an error in the bore., , P&M : Fitter - Related Theory for Exercise 1.2.33, , Copyright Free Under CC BY Licence, , 95
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.34, , Depth micrometer, Objectives: At the end of this lesson you shall be able to, • name the parts of a depth micrometer, • state the constructional features of a depth micrometer, • read depth micrometer measurements., Constructional features, The depth micrometer consists of a stock on which a, graduated sleeve is fitted., The other end of the sleeve is threaded with a 0.5 mm, pitch `V' thread., A thimble which is internally threaded to the same pitch, and form, mates with the threaded sleeve and slides over, it., The other end of the thimble has an external step machined, and threaded to accommodate a thimble cap. (Fig 1), , Graduation and least count, On the sleeve a datum line is marked for a length of, 25 mm. This is divided into 25 equal parts and, graduated,each line representing one millimetre. Each fifth, line is drawn a little longer and numbered. Each line, representing 1 mm is further subdivided into two equal, parts. Hence each sub-division represents 0.5 mm., (Fig 3), , A set of extension rods is generally supplied. On each of, them the range of sizes that can be measured with that, rod, is engraved as 0-25, 25-50, 50-75, 75-100, 100-125, and 125-150., These extension rods can be inserted inside the thimble, and the sleeve., The extension rods have a collar-head which helps the rod, to be held firmly. (Fig 2), The measuring faces of the stock and the rods are, hardened, tempered and ground. The measuring face of, the stock is perfectly machined flat., The extension rods may be removed and replaced, according to the size of depth to be measured., , 96, , Copyright Free Under CC BY Licence
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The graduations are numbered in the reverse direction, to, that marked on an outside micrometer., The zero graduation of the sleeve is on the top and the, 25 mm graduation near the stock., The bevel edge of the thimble is also graduated. The, circumference is equally divided into 50 equal parts and, every 5th division line is drawn a little longer and numbered., The numbering is in the reverse direction and increases, from 0, 5,10,15, 25, 30, 35, 40,45 and 50 (0). (Fig 4), , This will be the smallest measurement that can be taken, with this instrument, and so, this is the accuracy of this, instrument., Reading of depth micrometer, Barrel reading, (1 mm division), , =, , 8 x 1 mm, , = 8.00 mm, , Sub division, =, (0.5 mm division), , 1 x 0.5 mm, , = 0.50 mm, , Thimble reading =, , 3 x 0.01 mm, , = 0.03 mm, , (Thimble division x L.C) Total reading, , = 8.53 mm, , In barrel reading main division and sub, division have been hidden covered by thimble, Uses of depth micrometer, , • Depth micrometers are special micrometers used to, measure, , • the depth of holes., • the depth of grooves and recesses, • the heights of shoulders or projections., , The advancement of the extension rod for one full turn of, the thimble is one pitch which is 0.5 mm., Therefore, the advancement of the extension rod for, one division movement of the thimble will be equal to, 0.5 / 50 = 0.01 mm., , Digital micrometers, Objectives: At the end of this lesson you shall be able to, • state the uses of digital micrometer, • list the parts of digital micrometer, • read the reading from LED display and thimble and barrel, • brief the maintenance, maintenance of digital micrometers., Digital micrometers is one of the simplest and most widely, used measuring equipment in any manufacturing industry., Its simplicity and the versatile nature make Digital, Micrometers so popular. Different kinds of Digital, Micrometers available in the market., Feature of digital micrometers (Fig 1), •, , LCD displays measuring data and makes direct read, out with resolution of 0.001mm., , • Origin setting mm/inch conversion, switch for absolute, and incremental measurement., •, , Carbide tipped measuring faces., , •, , Ratchet ensures invariable measurement and accurate, repeatable reading, , Accuracy of digital micrometers, Digital micrometers provide 10 times more precision and, accuracy : 0.00005 inches or 0.001mm resolution, with, 0.0001 inches or 0.001mm accuracy., , P&M : Fitter - Related Theory for Exercise 1.2.34, , Copyright Free Under CC BY Licence, , 97
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Reading of the digital micrometer, , Maintenance of a digital micrometers, , The digital micrometers are provided with high precision, reading with LCD display. The reading is 14.054 mm as, shown in Fig 2., , Never apply voltage (e.g. engraving with an electric pen), on any part of the Digital Micrometers for fear of damaging, the circuit., Press the ON/OFF button to shut the power when the, Digital Micrometers stands idle; take out the battery if it, stands idle for a long time., , Reading also by reading the marks on the sleeve and the, thimble. Usually, the reading from the large LCD display, for the digital micrometer because the digital reading is, more accurate. The reading on the sleeve and the thimble, is just for reference. Read the markings on the sleeve, and the thimble, firstly, read the point which the thimble, stops at it on the right of the sleeve (It is 14mm here,, because each line above the centre long line represents, 1mm while each line below the centre long line represent, 0.5mm) (Fig 3), , As for the battery, abnormal display (digit flashing or even, no display) shows a flat battery. Thus you should push, the battery cover as the arrow directing and then replace, with a new one. Please note that the positive side must, face out If the battery bought from market dosen’t work, well (the power may wear down because of the long-term, storage or the battery’s automatic discharge and etc.), Please do not hesitate to contact the supplier., Flashing display shows dead battery. If this is the case, please replace the battery at once. No displace shows, poor contact of a battery or short circuit of both poles of, the battery. Please check and adjust pole flakes and, battery insulator cover. In case water enters the battery, cover, open the cover immediately and blow the inside of, the battery cover at a temperature of not more than 40ºC, till it gets dry., , Secondly, read the markings on the thimble, It is between, 5 and 6, So you need to estimate the reading. (It is, 0.054mm for each line here represents 0.001mm). At, last, add all the reading up : 14mm + 0.054 mm =, 14.054mm. So the total reading is 14.054mm., , 98, , P&M : Fitter - Related Theory for Exercise 1.2.34, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.35, , Vernier calipers, Objectives : At the end of this lesson you shall be able to, • name the parts of a vernier caliper, • describe the parts of a vernier calipers, • state the uses of a vernier caliper., A vernier caliper is a precision measuring instrument. It is, used to measure up to an accuracy of 0.02 mm. (Fig 1), , Vernier slide (5): A vernier slide moves over the beam, and can be set in any position by means of a springloaded thumb lever., Beam (6): The vernier slide and the depth bar attached to, it, slide over the beam. The graduations on the beam are, called the main scale divisions., Depth bar (7) (Fig 4):The depth bar is attached to the, vernier slide and is used for measurement of depth., , Parts of a vernier caliper, (Numbers as per Fig 1), Fixed jaws (1 and 2): Fixed jaws are part of the beam, scale. One jaw is used for taking external measurements,, and the other for taking internal measurements., Movable jaws (3 and 4): Movable jaws are part of the, vernier slide. One jaw is used for external measurements,, and the other for internal measurements. (Figs 2 and 3), , Thumb lever (8): The thumb lever is spring-loaded which, helps to set the vernier slide in any position on the beam, scale., Vernier scale (9): The vernier scale is the graduation, marked on the vernier slide. The divisions of this scale are, called vernier divisions., Main scale: The main scale graduations or divisions are, marked on the beam., Sizes: Vernier calipers are available in sizes of 150 mm,, 200, 250, 300 and 600 mm. The selection of the size, depends on the measurements to be taken. Vernier, calipers are precision instruments, and therefore, extreme, care should be taken while handling them., Never use a vernier caliper for any purpose other than, measuring., Vernier calipers should be used only to measure machined, or filed surfaces., They should never be mixed with any other, tools., Clean the instrument after use, and store it in a, box., , 99, , Copyright Free Under CC BY Licence
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Graduations and reading of vernier calipers, Objectives : At the end of this lesson you shall be able to, • determine the least count of a vernier caliper, • state how graduations are made on a vernier caliper with 0.02 mm least count, • read vernier caliper measurements., Vernier calipers: Vernier calipers are available with, different accuracies. The selection of the vernier caliper, depends on the accuracy needed and the sizes of the job, to be measured., , Fig 2 shows the graduations of a common type of vernier, caliper with a least count of 0.02 mm. In this, 50 divisions, of the vernier scale occupy 49 divisions (49 mm) on the, main scale., , This accuracy/least count is determined by the graduations, of the main scale and the vernier scale divisions., , Example, Calculate the least count of the vernier given in Fig 2., , Vernier Principle: The vernier principle states that two, different scales are constructed on a single known length, of line and the difference between them is taken for fine, measurements., Determining the least count of vernier calipers: In, the vernier caliper shown in Fig 1 the main scale divisions, (9 mm) are divided into 10 equal parts in the vernier scale., i.e. One main scale division (MSD) = 1 mm, One vernier scale division (VSD) = 9/10 mm, , Least count = 1 mm - 49/50 mm, = 1/50 mm, , Least count = 1 MSD - 1 VSD, , = 0.02 mm., , = 1 mm - 9/10 mm, , Example for reading vernier caliper (Fig 3), , = 0.1 mm, The difference between one MSD and one VSD = 0.1 mm, , Main scale reading = 60 mm, The vernier division coinciding with the main scale is the, 28th division, value = 28 x 0.02mm, = 0.56 mm, Reading, Total Reading, , = 60 + 0.56, = 60.56 mm, , Reading vernier measurements: Vernier calipers are, available with different graduations and least counts. For, reading measurements with a vernier caliper, the least, count should be determined first. (The least count of, calipers is sometimes marked on the vernier slide), 100, , P&M : Fitter - Related Theory for Exercise 1.2.35, , Copyright Free Under CC BY Licence
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The british system of measurement, Objectives : At the end of this lesson you shall be able to, • name the different units and multiples of liner mesasurements in the Birtish System, • state the metric equivalent of the unit in the inch system, The metric system for measurement is most widely used, for industrial measurements. But in certain industries, the, British system of measurement is still being used., In this system of measurement, the inch, its multiples, and sub-divisions are used to represent length, measurements., 36 inches or 3 feet make 1 yard. 5280 feet or 1760 yards, make 1 mile., , 0.00001 one hundred housands, 0.000001 one millionth (one micro inch), Example of conversion (Metric to inch), 1) .05mm = .00196 inch (.05x03937 = 0.0019685 inch), 2) 1.25m = 49.215 inch (1.25x39.37 = 49.215 inches), Example of conversion (Inch to Metric), , Coversions from inch to metric and vice versa, , 1) 3/4" = .75" = 19.05 mm (.75x 25.4 = 19.05 mm), 2) 1/1000" = 0.001 = 0.0254 mm (.001x25.4 = 0.0254mm), , CONVERSION FACTORS, , (One thousandth of an inch = 25 micrometre approx), , 1", 1 yard, 1 mm, , = 25.4 mm or 2.54 cm, = 36" or 0.9144 m, = 0.03937", , 1 metre, , = 1000 mm or 39.37", , FRACTIONS/DECIMALS EQUIVALENT, 1/64", 1/32", 1/16", 1/8", 1/4", 1/2", , =, =, =, =, =, =, , 0.015625", 0.03125", 0.0625", 0.125", 0.25", 0.5", , ASSIGNMENT, Convert the following., 1), 2), 3), 4), , 38.1mm, 300 mm, 8", 40", , =_______ inches, =_______ inches, =_______ mm, =_______ mm., , 5) Express the tolerance ± .05" in metric terms to the, nearest mm. _______________________________, 6) Express the tolerance .02 mm in terms of inches to, the nearest 1/10,000". _______________________, , 1.00 unit inch, 0.1 one tenth, 0.01 one hundredth, 0.001 one thousandth, 0.0001 one ten thousandth, , Reading vernier caliper and micrometer with inch graduations, Objectives : At the end of this lesson you shall be able to, • state the graduations of vernier calipers in the inch system, • state the graduations of micrometers in the inch system, • read the measurement of vernier calipers and micrometers with inch graduations., Reading vernier caliper and micrometer, The universal vernier calipers generally used in machine, shop will have graduations in both metric units and inches., The vernier caliper with inch graduation will have a least, count of 0.001"., The vernier scales for these calipers have graduation with, 25 division or 50 divisions., , Least count, , Vernier caliper with 25 divisions in vernier scale., (Fig.1), , 25 vernier scale divisions, , = 49 x 0.025 = 1.225", , One inch of the mainscale is divided into 10 major divisions,, and each of these is further divided into 4 equal parts. The, value of each sub-division is 0.025 inch. Such 49 divisions, of the main scale are equal to 25 divisions of the vernier, scale., , Value of vernier scale division, , = 0.049", , Value of 2 main scale divisions = 0.025 x 2 = 0.50", Least count = Value of main scale divison value of 1 vernier scale division, = 0.05" - 0.049" = 0.001" or 1/1000", , P&M : Fitter - Related Theory for Exercise 1.2.35, , Copyright Free Under CC BY Licence, , 101
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Example of reading (Fig 2), , Vernier '0' line is after 1" on the main scale, Full inch, = 1.000", The value of 4 major divisions, (4 x 0.1") =, The value of 1 subdivision, (1 x 0.05") =, The value of 9th vernier dividion, coinciding, (9 x 0.001") =, Reading, , .400", .050", .009", 1.459", , Micrometer with graduations in inches, On micrometers with grduations in the inch system, the, datum line on the barrel of the micrometer is graduated to, a distance of 1 inch. This one inch is divided into 10 equal, parts, and each of this is futher subdivided into 4 equal, parts. (Fig 5), In Figure 2 the vernier '0' line is after 1" on the scale, Full inch, 2 main scale divisions, Value of 1 subdivision, coinciding, , (13 x 001"), Reading, , = 1.000", = .200", = .025", = .013", 1.238", , In the vernier caliper given in fig 3 (50 divisions vernier, scale), each inch of the main scale is divided into 10 major, divisions, and they are further ssub - divided into two equal, parts. The value of each subdivision is 0.05". 50 dividions, of the vernier scale are equal to 49 sub divisions of the main, scale., , Least count, Value of 50 V.S.D., = 49 x 0.05, = 2.45", 1.V.S.D., = 2.45"/50, = 0.049", Least count = Value of 1 MSD - Value of 1 VSD, = 0.05" - 0.049 = 0.001", Example of reading (Fig 4), , The value of each subdivision = 1/40" or 0.025". The thimble, had 25 equal divisions marked on the circumference. The, least counet is = 1/40"x1/25 = 1/1000" =.001'., When the spindle of the micrometer advances by one, division on the thimble, the actual value of the linear, movement is = .001"., Example of reading (Fig 6), , Main divisions, Subdivisions, Thimble divisions, , 3 x .1, 2 x .025, 9 x .001, , Reading, , = .300", = .05", = .009", = .359", , The barrel is graduated into 10 equal divisions each of, which is further subdivided into 4 smaller divisions. The, length of the sleeve graduations is 1". It is the distance the, thimble travels in 40 complete revolutions., Barrel main divisions = 1/10 of an inch or 0.100" the, distance the thimble moves in four complete revolutions.The, thimble has 25 equal graduations on its circumference., Each graduation of the thimble is equal to 1/25 of 1/40 or, 0.001"., , 102, , P&M : Fitter - Related Theory for Exercise 1.2.35, , Copyright Free Under CC BY Licence
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Barrel subdivision 1/40 or 0.025 of an inch is equal to the, distance the thimble moves in one complete revolution. The, spindle screw has 40 TPI., , Answer, , ....................inch., , 2 Read and record the measurements of an outside, micrometer shown in the Figures 9 and 10., , Assignment, 1 Read the vernier caliper measurement as shown in, Figures 7 and 8., , Answer, , Answer, , ....................inch., , Answer, , ....................inch., , ....................inch., , Vernier height gauge, Objectives: At the end of this lesson you will be able to, • name the parts of a vernier height gauge, • state the constructional features of a vernier height gauge, • state the functional features of a vernier height gauge, • state the various applications of the vernier height gauge in engineering., Parts of a vernier height gauge (Fig 1), A, Beam, B, Base, C, Main slide, D, Jaw, E, Jaw clamp, F, Vernier scale, G, Main scale, H, Finer adjusting slide, I, Finer adjusting nut, J&K, Locking screws, L, Scriber blade, , Constructional features of a vernier height gauge:, The construction of a vernier height gauge is similar to, that of the vernier caliper that it is vertical with a rigid base., It is graduated on the same vernier principle which is, applied to the vernier caliper., The beam is graduated with the main scale in mm as well, as in inches. The main slide carries a jaw upon which, various attachments may be clamped. The jaw is an integral, part of the main slide., The vernier scale is attached to the main slide which has, been graduated, to read metric dimensions as well as the, inch dimensions. The main slide is attached with the finer, adjusting slide. The movable jaw is most widely used with, , P&M : Fitter - Related Theory for Exercise 1.2.35, , Copyright Free Under CC BY Licence, , 103
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obtaining the exact markable dimension, the main slide is, also to be locked in position., Modern vernier height gauges are designed on the screw, rod principle. In these height gauges, the screw rod may, be operated with the help of the thumb screw at the base., In order to have a quick setting of the main slide, it is, designed with a quick releasing manual mechanism. With, the help of this, it is possible to bring the slide to a desired, approximate height without wastage of time. For all other, purposes, these height gauges work as ordinary height, gauges. In order to set the ‘zero’ graduation of the main, scale for the initial reading., Some vernier height gauges are equipped with a sliding, main scale which may be set immediately for the initial, reading. This minimises the possible errors in reading the, various sizes in the same setting., Another kind of modern vernier height gauge has a rack, and pinion set up for operating the sliding unit. This is, shown in Fig 3., , the chisel pointed scriber blade for accurate marking out, as well as for checking the height, steps etc. Care should, be taken to allow for the thickness of the jaw depending, on whether the attachment is clamped on the top or under, the jaw for this purpose., The thickness of the jaw is marked on the instrument. As, like in a vernier caliper, the least count of this instrument, is also 0.02 mm. An offset scriber is also used on the, movable jaw when it is required to take measurement from, the lower planes. (Fig 2) The complete sliding attachment, along with the jaw can be arrested on the beam to the, desired height with the help of the locking screws. The, vernier height gauges are available in ranges of capacities, reading from zero to 1000 mm., , Various applications of a vernier height gauge: The, vernier height gauge is mainly used for layout work., (Fig 4), It is used for measuring the width of the slot and external, dimension., Functional features of the vernier height gauge:, Vernier height gauges are used in conjunction with the, surface plate. In order to move the main slide, both the, locking screws of the slide and the finer adjusting slide, have to be loosened. The main slide along with the chisel, pointed scriber has to be set by hand, for an approximate, height as required., , The vernier height gauge is used with the dial indicator to, check hole location, pitch dimensions, concentricity and, eccentricity., It is also used for measuring depth, with a depth, attachment., It is used to measure sizes from the lower plane with the, help of an offset scriber., , The finer adjusting slide has to be locked in position, for, an approximate height as required. To get an exact, markable height, the finer adjustments have to be carried, on the slider with the help of the adjusting nut. After, 104, , P&M : Fitter - RelatedTheory for Exercise 1.2.35, , Copyright Free Under CC BY Licence
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P&M : Fitter - Related Theory for Exercise 1.2.35, , Copyright Free Under CC BY Licence, , 105
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.36, , Vernier bevel protractor, Objectives : At the end of this lesson you shall be able to, • name the parts of a vernier bevel protractor, • state the functions of each part, • list out the uses of a vernier bevel protractor., The vernier bevel protractor is a precision instrument meant, for measuring angles to an accuracy of 5 minutes. (5'), Parts of a vernier bevel protractor, The following are the parts of a vernier bevel protractor., (Fig 1), , The vernier bevel protractor is used to measure acute angles, than 90º (Fig.2) obtuse angles more than 90o (Fig.3)., , Stock: This is one of the contacting surfaces during the, measurement of an angle. Preferably it should be kept in, contact with the datum surface from which the angle is, measured., Dial: The dial is an integrated part of the stock. It is circular, in shape, and the edge is graduated in degrees., Blade: This is the other surface of the instrument that, contacts the work during measurement. It is fixed to the, dial with the help of the clamping lever. A parallel groove is, provided in the centre of the blade to enable it to be, longitudinally positioned whenever necessary., , For setting work-holding devices to angles on machine, tools, work tables etc., (Fig 4 & Fig 5), , Locking screws: Two knurled locking screws are provided,, one to lock the dial to the disc, and the other to lock the, blade to the dial.., All parts are made of good quality steel, properly heattreated and highly finished. A magnifying glass is, sometimes fitted for clear reading of the graduations., Uses of a vernier bevel protractor: Apart from being, used for measuring angles a vernier bevel protractor is, also used for setting work-holding devices on machine, tools, work-tables etc., , 106, , Copyright Free Under CC BY Licence
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Graduations on universal bevel protractor, Objectives: At the end of this lesson you will be able to, • state the main scale graduations on the disc, • state the vernier scale graduations on the dial, • determine the least count of the vernier bevel protractor., The main scale graduations (Fig 1 & 2): For purposes, of taking angular measurements, the full circumference of, the dial is graduated in degrees. The 360° are equally, divided and marked in four quadrants, from '0' degree to 90, degrees, 90 degrees to '0' degree. Every tenth division is, marked longer and numbered. Each division represents 1, degree. The graduations on the dial are known as the main, scale divisions. On the disc, 23 divisions spacing of the, main scale is equally divided into 12 equal parts on the, vernier. Each 3rd line is marked longer and numbered as, 0, 15, 30, 45, 60. This constitutes the vernier scale. Similar, graduations are marked to the left of '0' also. (Fig 1), Hence the least count is, 2 MSD - 1 VSD, i.e the least count = 2º, , =, For any setting of the blade and stock, the reading of the, acute angle and the supplementary obtuse angle is, possible, and the two sets of the vernier scale graduations, on the disc assist to achieve this. (Fig 3), , One vernier scale division VSD (Fig 2), The least count of the vernier bevel protractor: When, the zero of the vernier scale coincides with the zero of the, main scale, the first division of the vernier scale will be, very close to the 2nd main scale division. (Fig 2), , P&M : Fitter - Related Theory for Exercise 1.2.36, , Copyright Free Under CC BY Licence, , 107
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Reading of universal bevel protractor, Objectives: At the end of this lesson you will be able to, • read a vernier bevel protractor for acute angle setting, • read a vernier bevel protractor for obtuse angle setting., For reading acute angle set up (Fig 1): First read the, number of whole degrees between zero of the main scale, and zero of the vernier scale., , For obtuse angle set up (Fig 3), , The vernier scale reading up is taken on the left side as, indicated by the arrow (Fig 4). The reading value is, subtracted from 180º to get the obtuse angle value., Note the line on the vernier scale that exactly coincides, with any one of the main scale divisions and determine its, value in minutes. (Fig 2), , Reading 22º 30’, Measurement 180º-22º30’=157”30’, , Care and maintenance of vernier bevel protractor, To take the vernier scale reading, multiply the coinciding, divisions with the least count., Example, 10 x 5' = 50', Total up both the readings to get the measurements=41°50'., If you read the main scale in an anticlockwise direction,, read the vernier scale also in an anticlockwise direction, from zero., , 108, , 1 Clean the vernier bevel protractor before use., 2 Loosen the locking screw of dial to move the blade, according to the angle measurment., 3 While taking a measurment apply light pressure on, vernier bevel protractor, 4 Heavy pressure will force the two scales out of parallel, and show the false reading., 5 After using vernier bevel protractor wipe it clean and, apply a thin coating of oil and keep it in safe place., , P&M : Fitter - Realted Theory for Exercise 1.2.36, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.37, , Dial Caliper, Objectives: At the end of this lesson you shall be able to, • state the advantages of a dial caliper over a vernier caliper, • state the constructional features of a dial caliper, • read the dial caliper., A dial caliper is a direct reading instrument which, resembles the vernier caliper. It is faster and easier to, read a dial caliper than to read the traditional vernier, caliper. (Fig 1), , The beam scale is graduated into 5mm increments on, 0.05 mm accuracy caliper, , Constructional features of dial caliper, , Care and maintenance of dial caliper, , The resemblance of a dial caliper is similar to normal, Vernier caliper, but with additional construction of a rack, mounted over the beam scale which is engaged to a pinion, of the dial. The dial pointer is actuated by the movable, action of vernier slide unit fixed with dial gauge., , 1 Clean the dial caliper with a soft cloth before use., 2 Apply a small drop of oil to the beam, rack and pinion, of the dial caliper to slide freely., , The caliper dial on the movable jaw is graduated into 100, equal divisions. The hand of the dial makes one complete, revolution for each 5 mm. Therefore, each dial graudation, represents 1/100th of 5mm or 0.05 mm., The dial hand is operated by a pinion that engages a rack, on the beam., Dial calipers are available in various sizes like vernier, calipers. A dial caliper with 0.02 mm accuracy is also, avaliable., For reading a measurement (Fig 2), Read the beam scale reading (25 mm) and add the reading, shown by the hand of the dial. 24 x 0.05 = 1.2mm, , 3 Check calibration of dial caliper, make sure that it is, working correctly., 4 After using dial caliper, wipe it with a clean dry cloth,, apply a thin coating of oil on sliding parts and keep it in, safe place., , Reading = 25+1.2 mm = 26.2 mm., , 109, , Copyright Free Under CC BY Licence
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The digital caliper, Objectives : At the end of this lesson you shall be able to, • state the uses of digital caliper, • name the parts of a digital caliper, • brief the zero setting of a digital caliper, The digital Caliper (sometime incorrectly called the digital, vernier caliper) is a precision instrument thant can be used, to measure internal and external distance accurately to, 0.01 mm, The digital vernier caliper is shown in fig 1, The, distance or the measurements are read from LCD/LED, display. The parts of digital calipers are similar to the, ordinary vernier caliper except the digital display and few, other parts., Part of Digital Caliper (Fig 1), 1.Internal jaws, 2.External jaws, , The digital caliper requires a small battery whereas the, manual version does not need any power source. The, digital calipers are easier to use as the measurement is, clearly displayed and also, by pressing inch/mm button the, distance can be read as metric or inch., Zero setting of Digital Caliper, The display is turned on with the ON/OFF button. Before, measuring, the zero setting to be done, by bringing the, external jaws together untill they touch each other and then, press the zero button. Now the digital caliper is ready to, use., , 3.Power On / Off button, , Caution, , 4.Zero Setting button, , Always set zero position when turning on the, display for the first time., , 5.Depth measuring blade, 6.Beam scale, 7.LED/ LCD Display, 8.Locking screw, 9.Metric/Inch button., , 110, , P&M : Fitter - Realted Theory for Exercise 1.2.37, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.38, , Drilling processes - Drilling Machines, Types, Use and Care, Objectives: At the end of this lesson you shall be able to, • name the various types of drilling machines, • name the parts of the bench and pillar type drilling machines, • compare the features of the bench and pillar type drilling machines., The principle types of drilling machines are, – the sensitive bench drilling machine, – the pillar drilling machine, – the column drilling machine, – the radial arm drilling machine (radial drilling machine)., (You are not likely to use the column and radial type of, drilling machines now. Therefore, only the sensitive and, pillar type machines are explained here), The sensitive bench drilling machine (Fig 1), The simplest type of the sensitive drilling machine is shown, in the figure with its various parts marked. This is used for, light duty work., This machine is capable of drilling holes up to 12.5 mm, diameter. The drills are fitted in the chuck or directly in, the tapered hole of the machine spindle., For normal drilling, the work-surface is kept horizontal. If, the holes are to be drilled at an angle, the table can be, tilted. (Tilting arrangemented is shown in Fig.1), , Different spindle speeds are achieved by changing the belt, position in the stepped pulleys. (Fig 2), , The pillar drilling machine (Fig 3): This is an enlarged, version of the sensitive bench drilling machine. These, drilling machines are mounted on the floor and driven by, more powerful electric motors., , They are also used for light duty work. Pillar drilling, machines are available in different sizes. The larger, machines are provided with a rack and pinion mechanism, to raise the table for setting the work., , 111, , Copyright Free Under CC BY Licence
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Drill - Holding devices, Objectives : At the end of this lesson you shall be able to, • name the types of drill-holding devices, • state the features of drill chucks, • state the functions of drill sleeves, • state the function of drift., For drilling holes on materials, the drills are to be held, accurately and rigidly on the on the machines., The common drill-holding devices are drill chucks and, sleeves and sockets., Drill Chuck, Straight shank drills are held in drill chucks. For fixing and, removing drills, the chucks are provided either with a pinion, and key or a knureld ring., The drill chucks are held on the machine spindle by means, of an arbor fitted on the drill chuck. (Fig 1), , Sleeves and sockets are made with the same taper so that, the taper shank of the drill, when engaged, will give a good, wedding action. Due to this reason morse tapers are called, self-holding tapers., Drills are provided with five different sizes of morse tapers,, and are numbered from MT1 to MT5., In order to make up the difference in sizes between the, shanks of the drills and the type of machine spindies,, sleeves of different sizes are used. When the drill taper, shank is bigger than machine spindle, taper sockets are, used. (Fig 1), , Taper Sleeves and Sockets (Fig 1), Taper shank drills have a morse taper., , 112, , P&M : Fitter - Realted Theory for Exercise 1.2.38, , Copyright Free Under CC BY Licence
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While fixing the drill in a socket or sleeve, the tang portion, should align in the slot. (Fig 2) This will facilitate the removal, of drill or sleeve from the machine spindle., , While removing the drill from the sockets/, sleeves, don't allow it to fall on the table or, jobs. (Fig 4), , Use a drift to remove drills and sockets from the machine, spindle. (Fig 3), , Work-holding devices, Objectives : At the end of this lesson you shall be able to, • state the purpose of work-holding devices, • name the devices used for holding work, • state the precautions to be observed while using work-holding devices., Workpieces to be drilled should be properly held or, clamped to prevent from roating along with the drill., Improperly secured work is not only a danger to the, operator but can also cause inaccurate work, and breakage, to the drill. Various are used to ensure proper holding., , Workpieces which are not accurate may be supported by, wooden pieces. (Fig 2), , The machine vice, Most of the drilling work can be held in a machine vice., Ensure that the drill does not drill through the vice after it, has passed through the work. For this purpose, the work, can be lifted up and secured on paralle blocks providing a, gap between the work and the bottom of the vice. (Fig 1), , Clamps and bolts, Driling machine tables are provided with T-slots for fitting, bolt heads. Using clamps and bolts, the workpieces can, be held very rigidly. (Fig 3) While using this method, the, P&M : Fitter - Realted Theory for Exercise 1.2.38, , Copyright Free Under CC BY Licence, , 113
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There are many types of clamps and it is necessary to, determine the clamping method according to the work., (Fig 5& 6), , packing should be, as far as possible, of the same height, as the work, and the bolt nearer to the work. (Fig 4), , Cutting speed and RPM, Objectives : At the end of this lesson you shall be able to, • define cutting speed., • state the factors for determining the cutting speed, • differentiate between cutting speed and RPM, • determine RPM/spindle speed, • select RPM for drill sizes from tables., For a drill to give a satisfactory performance, it must, operate at the correct cutting speed and feed., , Tool manufacturers usually provide a table of cutting, speeds required for different materials., , Cutting speed is the speed at which the cutting edge, passes over the material while cutting, and is expressed, in metres per minute., , The recommended cutting speeds for different materials, are given in the table. Based on the cutting speed, recommended, the RPM, at which a drill has to be driven,, is determined., , Cutting speed is also sometimes stated as surface speed, or peripheral speed., The selection of the recommended cutting speed for, drilling depends on the materials to be drilled, and the tool, material., 114, , P&M : Fitter - Realted Theory for Exercise 1.2.38, , Copyright Free Under CC BY Licence
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Materials, being drilled, for HSS, , Cutting, speed (m/min), , Aluminium, Brass, , 70 - 100, 35 - 50, , Bronze(phosphor), Cast iron (grey), Copper, , 20 - 35, 25 - 40, 35 - 45, , Steel (medium, carbon/mild steel), Steel (alloy,high, tensile), Thermosetting, plastic (low speed, due to abrasive, properties), , 20 - 30, , n=, , nxdxπ, 1000, , 5-8, , 20 - 30, , dxπ, , π = 3.14, Examples: Calculate the RPM for a high speed steel drill, ∅ 24 to cut mild steel., The cutting speed for MS is taken as 30 m/min. from the, table., n=, , 1000x30, 3.14x24, , = 398 RPM, , It is always preferable to set the spindle speed to the, nearest available lower range. The selected spindle speed, is300 RPM., The RPM will differ according to the diameter of the drills., The cutting speed being the same, larger diameter drills will, have lesser RPM and smaller diameter drills will have, higher RPM., The recommended cutting speeds are achieved only by, actual experiments., , m/min, , vx1000, , v - cutting speed in m/min., d - diameter of the drill in mm, , Calculating RPM, v=, , n - RPM, , RPM, , Feed in drilling, Objectives : At the end of this lesson you shall be able to, • state what is meant by feed, • state the factors that contribute to an efficient feed rate., Feed is the distance (X) a drill advances into the work in one, complete rotation. (Fig 1), , Finish required, Type of drill (drill material), Material to be drilled, Factors like rigidity of the machine, holding of the workpiece, and the drill, will also have to be considered while determining, the feed rate. If these are not to the required standard, the, feed rate will have to be decreased., It is not possible to suggest a particular feed rate taking all, the factors into account., The table for the feed rate given here is based on the, average feed values suggested by the different, manufacturers of drills. (Table 1), , Feed is expressed in hundredths of a millimeter., Example - 0.040mm, The rate of feed is dependent upon a number of factors., , P&M : Fitter - Realted Theory for Exercise 1.2.38, , Copyright Free Under CC BY Licence, , 115
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TABLE 1, Drill diameter, (mm) HSS, , Rate of feed (mm/rev), , 1.0 - 2.5, , 0.040, , - 0.060, , 2.6 - 4.5, , 0.050, , - 0.100, , 4.6 - 6.0, , 0.075, , - 0.150, , 6.1 - 9.0, , 0.100, , - 0.200, , 9.1 -12.0, , 0.150, , - 0.250, , 12.1 - 15.0, , 0.200, , - 0.300, , 15.1 - 18.0, , 0.230, , - 0.330, , 18.1 - 21.0, , 0.260, , - 0.360, , 21.1 - 25.0, , 0.280, , - 0.380, , Too coarse a feed may result in damage to the cutting, edges or breakage of the drill., Too slow a rate of feed will not bring improvement in surface, finish but may cause excessive wear of the tool point, and, lead to chattering of the drill., For optimum results in the feed rate while, drilling, it is necessary to ensure the drill cutting, edges are sharp. Use the correct type of cutting, fluid., , Radial drilling machines, Objectives : At the end of this lesson you shall be able to, • state the uses of a radial drilling machine, • state the features of radial drilling machine., Radial drilling machines are used to drill, , The arm is supported by a pillar (column). It can be rotated, , - large diameter holes, , about with the pillar as centre. Therefore, the drill spindle, can cover the entire working surface of the table. The arm, can be lifted or lowered., , - multiple holes in one setting of the work, - heavy and large workpieces., , The motor mounted on the spindle head rotates the, spindle., , Features (Fig 1), , The variable-speed gear box provides a large range of, R.P.M., The spindle can be roated in both clockwise and, anticlockwise directions., Angular holes can be drilled on machines having tilting, tables., A coolant tank is mounted on the base., , The radial drilling machine has a radial arm on which the, spindle head is mounted, , Precautions, Ensure that the spindle-head and the arms are, locked properly to avoid vibration., The workpiece and the drill should be rigidly, held., Bring back the spindle head nearer to the pillar, after use., Switch off power when not in use., Use the drill drift for removing the drills, chucks, or sockets., Use a minimum number of sockets and sleeves, to make for the spindle bore size., Clean and oil the machine after use., Stop the machine to remove the swarf., Use a brush to clean the chips and swarf., , The spindle head can be moved along the radial arm and, can be locked in any position, 116, , P&M : Fitter - Realted Theory for Exercise 1.2.38, , Copyright Free Under CC BY Licence
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Gang drilling machine and multiple spindle head drilling machine, Objectives: At the end of this lesson you shall be able to, • state the uses of a gang drilling machine, • state the construction of a gang drilling machine, • state the uses and construction of a multiple spindle head drilling machine., Gang drilling machine (Fig 1), , It consists of a large base supporting a long table. The top, of the table is designed in such a way that several units, may be mounted on it. Each spindle is driven by its, individual directly connected motor., The table has a groove around the outside for the return of, the cutting lubricant, and may have ‘T’-slots on its surface, for ease in clamping the work to the table., This type of machine is generally preferred when the work, is to be moved from spindle to spindle for successive, operations., , The multiple spindle head drilling machine is specially, designed for mass production operations such as drilling,, reaming or tapping many holes at one time in a specific unit, of work such as an automobile engine block., There may be two or more drill heads on one machine, each, with many spindles. This is necessary when holes are, drilled from more than one direction - for example, on the, top side, and the end of a piece of work. Production units, of this type are seldom used in a tool room that usually, does highly skilled work., , Multiple spindle head drilling machine (Fig 2), The multiple spindle head drilling machine may have any, number of spindles - from 4 to 48 or more, all driven from the, one-spindle drive gear in one head., , P&M : Fitter - Realted Theory for Exercise 1.2.38, , Copyright Free Under CC BY Licence, , 117
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.39, , Hand taps and wrenches, Objectives: At the end of this lesson you shall be able to, • state the uses of threading hand taps, • state the features of hand taps, • distinguish between different taps in a set, • name the different types of tap wrenches, • state the uses of diffrerent types of wrenches., Use of hand taps, Hand taps are used for internal threading of components., Features (Fig 1), They are made from high carbon steel or high speed steel,, hardened and ground., Threads are cut on the surface, and are accurately finished., , These are, first tap or taper tap, second tap or intermediate tap, plug or bottoming tap., These taps are identical in all features except in the taper, lead., , To form the cutting edges, the flutes are cut across the, thread., For holding and turning the taps while cutting threads, the, ends of the shanks are squared., The ends of the taps are chamfered (taper lead) for, assisting, aligning and starting of the thread., The size of the taps and the type of the thread are usually, marked on the shank., , The taper tap is to start the thread. It is possible to form, full threads by the taper tap in through holes which are not, deep., The bottoming tap (plug) is used to finish the threads of, a blind hole to the correct depth., For identifying the type of taps quickly - the taps are either, numbered as 1, 2 and 3 or rings are marked on the shank., The taper tap has one ring, the intermediate tap has two, rings and the bottoming tap has three rings. (Fig 2), Tap Wrenches, , In certain cases, the pitch of the thread will also be, marked., , Tap wrenches are used to align and drive the hand taps, correctly into the hole to be threaded., , Markings are also made to indicate the type of tap i.e. first,, second or plug., , Tap wrenches are of different types., , Types of Taps in a set, , Double ended adjustable wrench, T-handle tap wrench,, solid type tap wrench., , Hand taps for a particular thread are available as a set, consisting of three pieces. (Fig 2), , Double-ended Adjustable Tap Wrench or Bar Type, Tap Wrench (Fig 3), , 118, , Copyright Free Under CC BY Licence
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This is the most commonly used type of tap wrench. It is, available in various sizes. These tap wrenches are more, suitable for large diameter taps, and can be used in open, places where there is no obstruction to turn the tap. It is, important to select the correct size of wrench., T-Handle tap wrench (Fig 4), , These are small adjustable chucks with two jaws and a, handle to turn the wrench., This tap wrench is useful to work in restricted places, and, is turned with one hand only., This wrench is not available for holding large diameter taps., Solid type tap wrench (Fig 5), These wrenches are not adjustable., They can take only certain sizes of taps. This eliminates, the use of wrong length of the tap wrenches, and thus, prevents damage to the taps., , Tap drill size, Objectives: At the end of this lesson you shall be able to, • state what is tap drill size, • choose the tap drill sizes of different threads from tables, • calculate the tap drill sizes for ISO metrice and ISO inch., What is a tap drill size?, Before a tap is used for cutting internal threads, a hole is, to be drilled. The diameter of the hole should be such that, it should have sufficient material in the hole for the tap to cut, the thread., , Further it also requires a greater force for turning the tap if, a higher percentage formation of thread is required., Considering this aspect, a more practical approach for, determining the tap drill sizes is, Tap drill size = Major diameter – pitch, , Tap drill sizes for different threads, , = 10 mm - 1.5 mm, , ISO Metric Thread, , = 8.5 mm., , Tapping drill size, for M10 x 1.5 thread, , Compare this with the table of tap drill sizes for ISO, metric threads., , Minor diameter = Major diameter – 2 x depth, , ISO Inch (Unified) threads Formula, , depth of thread = 0.6134 x pitch of a screw, , Tap Drill size =, , 2 depth of thread = 0.6134 x 2 x pitch, Major diameter −, , =1.226 x 1.5 mm = 1.839 mm, Minor dia (D1)=10 mm – 1.839 mm, =8.161mm or 8.2 mm, This tap drill will produce 100% thread because this is, equal to the minor diameter of the thread. For most, fastening purposes a 100% formed thread is not required., , 1, Number of threads per inch, , For calculating the tap drill size for 5/8" UNC thread, Tap drill size = 5/8" – 1/11", = 0.625" – 0.091", = 0.534", , A standard nut with 60% thread is strong enough to be, tightened until the bolt breaks without stripping the thread., P&M : Fitter - Realted Theory for Exercise 1.2.39, , Copyright Free Under CC BY Licence, , 119
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The next drill size is 17/32" (0.531 inches), Compare this with the table of drill sizes for unified inch, threads., , Refer to chart for determining the pitches of, the thread., , What will be the tapping size for the following threads?, (a), , M 20, , (b), , UNC 3/8, COMMERCIAL DRILL SIZES ISO INCH (UNIFIED) THREAD, NC National Coarse, Tap size, , Tharads, per inch, , NF National Fine, Tap dirll size, per inch, , Tap size, , Therads, , Tap drill size, , 5, , 40, , 38, , 5, , 44, , 37, , 6, , 32, , 36, , 6, , 40, , 33, , 8, , 32, , 29, , 8, , 36, , 29, , 10, , 24, , 25, , 10, , 32, , 21, , 12, , 24, , 16, , 12, , 28, , 14, , 1/4 ", , 20, , 7, , 1/4 ", , 28, , 3, , 5/16 ", , 18, , F, , 5/16 ", , 24, , 1, , 3/8 ", , 16, , 5/16 ", , 3/8 ", , 24, , 0, , 7/16 ", , 14, , U, , 7/16 ", , 20, , 25/64 ", , 1/2 ", , 13, , 27/64 ", , 1/2 ", , 20, , 29/64 ", , 9/16 ", , 12, , 31/64 ", , 9/16 ", , 18, , 33/64 ", , 5/8 ", , 11, , 17/32 ", , 5/8 ", , 18, , 37/64 ", , 3/4 ", , 10, , 21/32 ", , 3/4 ", , 16, , 11/16 ", , 7/8 ", , 9, , 49/64 ", , 7/8 ", , 14, , 13/16 ", , 1", , 8, , 7/8 ", , 1", , 14, , 15/16 ", , 1 1/8 ", , 7, , 63/64 ", , 1 1/8 ", , 12, , 1 3/6 ", , 1 1/4 ", , 7, , 17/64 ", , 1 1/4 ", , 12, , 1 11/6 ", , 1 3/8 ", ", , 6, , 17/32 ", , 1 3/8 ", , 12, , 1 19/64, , 1 3/4 ", , 5, , 1 9/16 ", , 2", , 4 1/2, , 1 25/32 ", NPT National pipe thread, , 1/8 ", , 27, , 11/32 ", , 1", , 11 1/2, , 1 5/32 ", , 1/4 ', , 18, , 7/16 ", , 1 1/4 ", , 11 1/4, , 1 1/2 ", , 3/8 ", , 18, , 19/32 ", , 1 1/2 ", , 11 1/2, , 1 23/32 ", , 1/2 ", , 14, , 23/32 ", , 2", , 11 1/2, , 2 23/16 ", , 3/4 ", , 14, , 15/16 ", , 2 1/2 ", , 8, , 2 5/8 ", , 120, , P&M : Fitter - Realted Theory for Exercise 1.2.39, , Copyright Free Under CC BY Licence
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TABLE FOR TAP DRILL SIZES- ISO METRIC THREADS, , 121, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Basic Fitting, , Related Theory for Exercise 1.2.40-41, , Letter punch and number punch, Objective: At the end of this lesson you shall be able to, • state the uses of letter Punch and Number Punch, Metal stamps are used to mark or identify work pieces., They are available for stamping letters (Letter Punch) and, , Numbers (Number punch). They can not be used on, hardened metal surfaces (Fig.1), , The letter punch set consists of A, B, C, D, E, F, G, H, N,, I, J, K, L, M, N, O, P,Q, R, S, T, U, V, W, X, Y, Z, and '&', (Symbol) of 27 Letter punches in a set. The Number punch, set consists of 0,1,2,3,4,5,6,7,8, the number punch 6 will, the used for punching number both 6 and 9 ., , or number (Fig.3) or space (Fig.4) a centre line should be, scribed on the base line (Fig.2) Letters or numbers before, stamping should be placed on either side of the line from, center line, so that middle letter is stamped over the, centreline large size letter number punchs are used for, better impression by applying more than one stroke. While, Punching on cast iron or hot rolled steel, the hard outer, layer of the metal should the removed by grinding or filing, or machining for better impression are visibility., , The letters and numbers are formed in the reverse order. So, that while punching letters and numbers will be in correct, position. A base line should be scribed on the metal, surface, before stamping the letter or number using these, punches. Also to locate the position of middle letter (Fig.2), , 122, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Sheet Metal, , Related Theory for Exercise 1.3.42, , Safety precautions in sheet metal workshop, Objectives: At the end of this lesson you shall be able to, • state various hazardous while working in a SMW shop, • state different precautions to be taken for safe working in a SMW shop., Whenever a work is done in a shop the following aspects, may create an injury to the workman/trainee or to others, working nearby., , – Keep a separate bin/basket for throwing cotton waste,, metal chips etc., , 1 Way of handling the materials, tools and machine., , – Always keep fire fighting equipment and the First Aid, Box ready for use in case of any emergency., , 2 Cleaning of the work area/shop floor., , – After completion of work keep the tools in the tool box., , 3 Damaged/faulty tools, machines and safety appliances., , – Wear helmet if anybody is working above your work, place, either to repair at the roof or on a overhead crane., , 4 Carelessness and negligence of the workman/trainee., 5 Ignorance of general safety rules., To avoid the accident/injuries taking place, while working, it is very important to follow certain safety precautions., They are:, – Do not bend your whole body while lifting heavy loads., Instead use your thigh muscles for lifting., – Use gloves while handling thin sheets., – Use chipping screen during chiseling operation., – Avoid using a mushroom head chisel., , – Use tongs while handling hot objects., – Do not try to check the sharpness of any tool with bare, fingers., – Switch off the mains of a machine while leaving the, machine after completion of work., – Do not try to rectify any electrical fault by yourself., Call an electrician for doing any electrical repair work., – Wherever and whenever possible avoid poluting the, environment., , – Arrange the tools properly over the work table so that, the tools are not allowed to fall from the table on your, foot., , – If any other person is affected by electric shock,, immediately switch off the mains or separate the person, from the electrical contact using a wooden rod or any, other insulating material., , – Wear proper size safety shoes., , – Always fix the job at a convenient height on the vice., , – Remove burrs by filing from a plate or sheet after cutting, them by chisel or hacksaw., , – Use sufficient leverage while tightening or loosening a, nut or bolt., , – Do not use a hammer with a broken or damaged handle., , General Workshop Rules, , – Fix the hammer head with the handle securely using a, wedge., , – Safety glasses must be worn., , – Do not wear loose garments/dress., , – Safety footwear must be worn when working in the, workshop., , – Wear plain goggles/face shield while grinding., , – Ask workshop instructor before using equipment., , – Do not grind materials which are 3mm or less in, thickness and non-ferrous metals., , – Visitors must remain within marked walkways., , – Adjust the gap between the work rest and the grinding, wheel to 1-2mm., – Select and use the right kind of tool for the right job., – Keep the floor on the work area neat and clean without, any cut pieces of material, oil, etc., , – Long hair must be tied back., – Clean, equipments & machines after use., – Take care when using compressed air., – Hearing protection should be worn when using, machinery., – Working alone after hours is not permitted., , 123, , Copyright Free Under CC BY Licence
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General safety precautions, Objectives: At the end of this lesson you shall be able to, • state what an accident is, • state the causes for accidents in general terms, • state what is safe attitude, • name the four basic categories of safety signs., What is an accident?, Nobody deliberately makes an accident; accidents occur, due to the causes which are not foreseen. Sometimes, nothing can be done to prevent them from happening. For, example, a part of a machine fails when nobody has any, reason to think there is anything wrong with it, or the driver, of a vehicle collapses at the wheel. Most accidents, however occur as the result of a human error, of ignorance, or neglect, forgetfulness or recklessness. These accidents, can be prevented. If people had acted differently at some, point, the event which we call an ‘accident’ would not have, occurred. (Fig 1), , Lots of accidents still happen every year killing a lot of, people. Although most people are alarmed and horrified, by this state of affairs, accidents continue to happen,, costing the industry millions of rupees every year. Older, workers who have come to terms with the dangers, young, workers who may be reckless, employers who turn a blind, eye to the possibility of things going wrong - because, they want to get the job done, all these factors contribute, to this senseless waste. Fortunately there are many who, do not take this view. They have a different attitude to, wards safety - and ‘attitude’ is an all-important factor in, the chain of events which leads to someone causing, being, involved in, or becoming the victim of an ‘accident’., , Safe attitudes: People’s attitudes govern what they do or, fail to do. In most cases where someone is working with, unsafe equipment or in an unsafe situation, somebody has, allowed that state of affairs to come about by something, they have done or failed to do. (Fig 4), , Causes for accidents: Normally accidents do not just, happen. They are caused. (Fig 2), Causes for accidents are many. Some of the important, causes are listed below. (Fig 3), —, , Unawareness of danger, , —, , Disregard for safety, , —, , Negligence, , —, , Lack of understanding of proper safety procedures, , —, , Untidy condition of workplace, , —, , Inadequate light and ventilation, , —, , Improper use of tools, , —, , Unsafe conditions, 124, , P&M : Fitter - Related Theory for Exercise 1.3.42, , Copyright Free Under CC BY Licence
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Most accidents don’t just happen; they are caused by, people who (for example) damage equipment or see it is, faulty but don’t report it, or leave tools and equipment, lying about for other people to trip over. Anybody who sees, a hazard and does nothing about it is also contributing to, the possibility of an accident. A worker doesn’t necessarily, need to do anything to bring about an accident; just going, mindlessly about his work may be enough to ensure a, work-mate being crippled for life. He didn’t do it - but by, proper and timely thinking and acting, he could have, prevented it., Responsibilities: Safety doesn’t just happen - it has to, be organised and achieved like the work-process of which, it forms a part. The law states that the employer and his, employees have the responsibility in this behalf., Employer's responsibililties: The effort a firm puts into, planning and organising work, training people, engaging, skilled and competent workers, maintaining plant and, equipment, and checking, inspecting and keeping records, - all of this contributes to the safety in the workplace., The employer is responsible for the equipment provided,, the working conditions, what employees are asked to do,, and the training given., Employee's responsibilities: You will be responsible, for the way you use the equipment, how you do your job,, the use you make of your training, and your general attitude, to safety., A great deal is done by the employers and other people to, make your working life safer; but always remember you, are responsible for your own actions and its effect on others., You must not take that responsibility lightly., Rules and procedures at work: What you must do, by, law, is often included in the various rules and procedures, laid down by your employer. They may be written down,, but more often than not, are just the way a firm does things, - you will learn these from other workers as you do your, job. They may govern the issue and use of tools,, protective clothing and equipment, reporting procedures,, emergency drills, access to restricted areas, and many, other matters. Such rules are essential; they contribute, to the efficiency and safety of the job., , The four basic categories of safety signs are as follows., —, , prohibition signs, , —, , mandatory signs, , —, , warning signs, , —, , information signs, , Prohibition signs Fig5, Shape, Colour, , Meaning, Example, , Circular., Red border and cross bar., Black symbol on white, background., Shows it must not be done., No smoking., , Mandatory signs Fig6, Shape, Colour, Meaning, Example, , Warning signs Fig7, Shape, Colour, Meaning, Example, , Circular., White symbol on blue, background., Shows what must be done., Wear hand protection., , Triangular., Yellow background with, black border and symbol., Warns of hazard or danger., Caution, risk of electric, shock., , Information signs Fig8, Shape, Colour, Meaning, Example, , Square or oblong., White symbols on green, background., Indicates or gives information of safety provision., First aid point., , Prohibition signs (Fig 9), , Safety signs: As you go about your work on a construction, site you will see a variety of signs and notices. Some of, these will be familiar to you - a ‘no smoking’ sign for, example; other signs you may not have seen before. It is, up to you to learn what they mean - and to take notice of, them. They warn of the possible danger, and must not be, ignored., Safety signs fall into four separate categories. These can, be recognised by their shape and colour. Sometimes they, may be just symbols other signs may include letters or, figures and provide extra information such as the clearance, height of an obstacle or the safe working load of a crane., , P&M : Fitter - Related Theory for Exercise 1.3.42, , Copyright Free Under CC BY Licence, , 125
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Mandatory signs (Fig 10), , Questions about your safety, Do you know the general safety rules that cover your place, of work?, Are you familiar with the safety laws that cover your, particular job?, Do you know how to do your work without causing danger, to yourself, your workmates and the general public?, Are the plant, machinery and tools that you use really, safe? Do you know how to use them safely and keep, them in a safe condition?, Do you wear all the right protective clothing, and have you, been issued with all the necessary safety equipment?, Have you been given all the necessary safety information, about the materials used?, Have you been given training and instruction to enable, you to do your job safely?, Do you know who is responsible for safety at your place of, work?, Do you know who are the appointed `Safety, Representatives'?, , Warning signs (Fig 11), , Importance of sheet metal work in industries, Objective : At the end of this lesson you shall be able to, • state the scope and the importance of the trade., Introduction, , – roofings, , Many engineering products are made out of sheet metal., The person who works on metal sheets is called sheet, metal worker. The skilled sheet metal worker make and, install various kind of sheet metal products. (Fig 1), , – ductings, , 126, , – vehicles body buildings like 3 wheelers, 4 wheelers,, ships, air crafts etc., , P&M : Fitter - Related Theroy for Exercise 1.3.42, , Copyright Free Under CC BY Licence
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– furnitures, – house hold articles, – railway equipment, Also repairing of the above items., To carry out these works, the sheet metal worker has to, plan, layout and determine the size and the type of the, sheet metal to be used., The sheet metal worker carries out the operations such, as cutting, folding, forming, fastening and assembling, manually and by means of power machines., The above requirements needs proper training and to know, the basic principles of operation and process. All the, advance technologies are developed from basic principles, only. The advance technologies facilitates for mass, production, consistance in accuracy of product and the, volume of needs., , Technical terms in sheet metal work, Objective : At the end of this lesson you shall be able to, • state the meaning of various terms used in sheet metal work., 1 Beading: The process of raising a strip of metal around, the end of a round pipe., , 14 Forming: The process of rolling sheet metal into pipe, or making bends to form objects., , 2 Bench machines: Machines clamped to a bench and, operated by turning a crank. Used by the sheet metal, worker to turn edges on circles and round pipes., , 15 Gauge: The system of classifying the thickness in, which sheet metal is produced. Also a tool used for, measuring and determining the thickness of a metal, sheet., , 3 Bench stakes: Steel anvils of various specialized, shapes that the sheet metal worker uses to form and, seam sheet metal objects., 4 Black iron: Iron and steel sheets covered with an, oxidized coating only., 5 Braising: The process of stretching a piece of metal by, hitting it with a round head hammer, as in forming a, bowl., , 16 Hem: A folded edge on a sheet metal object., 17 Layout work: The process of developing the pattern for, a sheet metal object., 18 Longitudinal seam: A seam running the long length, of a pipe., 19 Miter: The joining of two pieces at an evenly divided, angle., , 6 Brake: A machine that the sheet metal worker uses for, bending and folding edges on metal., , 20 Nibble: Nibble to piece metal along or on its edge., , 7 Burring: The process of turning an edge on a circular, piece of metal., , 21 Oxides of metal: A chemical formed by a combination, of the oxygen in the air with the metal. Iron rust is iron, oxide., , 8 Clips: Special strips of sheet metal bent in a manner, to connect two pieces of sheet metal duct., 9 Crimping: The process of corrugating the end of a, round pipe to make it smaller so it will fit into the end of, another pipe., , 22 Parallel line development: A method of pattern, drafting employing parallel lines., , 10 Cut acid: Zinc chloride, made by putting strips of zinc, in hydrochloric acid., , 23 Pattern: The shape of an object to be made out of sheet, metal as it appears when marked out on the flat sheet., Also, the exact size and shape that a piece of sheet, metal must be in order to be formed into the object, desired., , 11 Edges: Bends on the edges of sheet metal to eliminate, sharp edges and provide stiffening., , 24 Pickle: To clean dirt and oxide from metal by immersing it in an acid bath., , 12 Embossing: A stamping process that produces a, shallow relief design on sheet metal., , 25 Pictorial drawings: A drawing of an object in three, dimensions as it actually appears after being formed, into shape., , 13 Flux: Chemical used to clean metal and remove the, oxides from the metal surface prior to soldering., , 26 Pierce: To cut out interior waste stock from a metal, part with a die., 127, P&M : Fitter - Related Theroy for Exercise 1.3.42, , Copyright Free Under CC BY Licence
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27 Planish: To make a metal surface smooth by hammering it over a stake or block., , 38 Sheet metal: Any type of metal sheets that are 1/8", thick or less., , 28 Press brake: A power machine used by the sheet, metal worker to form sheet metal., , 39 Sheet metal screws: Special screws used for joining, sheet metal. Also called self-tapping because the, screws tap their own threads in the drilled hole., , 29 Press forming: Creating sheet metal products using, dies to cut and shape the metal and presses to power, the dies. Also called stamping., 30 Primer: A first coat of finish on a metal, it binds and, adhers to the metal giving good base for later coats., 31 Punching: The process of making holes in sheet metal, by the use of dies., 32 PVC (polyviny/chloride): A plastic often used for, hoods and tanks that require high corrosion resistance., 33 Radial line development: A method of pattern, drafting using lines radiating from a center and using, arcs., 34 Raw acid: Hydrochloric acid (HCI), 35 Rivets: Fasteners used to join two pieces of sheet, metal together. The rivet is inserted in a hole and a, head is formed by pounding the rivet with a hammer., 36 Seams: Various types of bent and hooked edges used, to join two pieces of sheet metal. For lighter sheet, metal, mechanical joints are used. In medium and, heavy gauge metal, a riveted or welded seam is used., 37 Seam welding: A kind of resistance welding in which, rollers are used instead of electrodes., , 128, , 40 Overlapping parts: Resistance to electricity, generates heat producing the weld., 41 Square-to-round: The name of a common sheet metal, fitting that is square or rectangular on one end and, round on the other end., 42 Stainless steel: A special steel containing other types, of metals such as chromium, nickel and molybdenum., There are many types of stainless steel sheets. All of, them vary in corrosion resistance., 43 Swage: A special forging tool used for smoothening, and finishing., 44 Sweat soldering: The process of soldering two pieces, of metal together by making the solder “sweat”, completely through the seam., 45 Tinning: Covering an area of metal with molten solder., 46 Transition piece: A sheet metal fitting that changes, size or shape from one end to the other., 47 Triangulation: A method of pattern drafting employing, the use of triangles., 48 Wired edge: A sheet metal edge folded around a piece, of wire for added strength., , P&M : Fitter - Related Theroy for Exercise 1.3.42, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Sheet Metal, , Related Theory for Exercise 1.3.43, , Metal sheets and their uses, Objectives:At the end of this lesson you shall be able to, • state the types of metals used in sheet metal work, • state the uses of the different types of metals., In sheet metal work, different types of metal sheets are, used. The sheets are specified by their standard gauge, numbers., It is very essential to know the different uses and applications of these metal sheets., Black iron sheets: The cheapest sheet metal is the black, iron, which is rolled to the desired thickness. The sheets, are rolled in two conditions. When it is rolled in cold state,, it is called cold rolled and when it is rolled in hot state, it, is called hot rolled. Hot rolled sheets have a bluish black, appearance, and are often referred to as uncoated sheets,, since they are uncoated. They corrode rapidly., Cold rolled sheets have plain silver whitish appearance and, are uncoated. To decrease the work hardness, the cold, ruled sheets are annealed in a closed atmosphere. These, sheets are known as C.R.C.A (Cold roled close annealed), sheets., The use of this metal is limited to making articles that are, to be painted or enamelled such as tanks, pans, stoves,, pipes etc., Galvanised iron sheets: Zinc coated iron is known as, ‘galvanised iron’. This soft iron sheet is popularly known, as G.I.sheet. The zinc coating resist corrosion and, improves the appearance of the metal and permit it to be, soldered with greater ease. Because it is coated with zinc,, galvanised iron sheet withstands contact with water and, exposure to weather., , Stainless steel is used in dairies, food processing, chemical plants, kitchenware etc., Copper sheets: Copper sheets are available either as cold, rolled or hot rolled. They have a very good resistance to, corrosion and can be worked easily. They are commonly, used in sheet metal shops. Copper sheet has better, appearance than other metals., Gutters, expansion joints, roof flashings, hoods, utensils, and boiler plates are some of the common examples where, copper sheets are used., Aluminium sheets: Aluminium cannot be used in its pure, form, but is mixed with very small amount of copper,, silicon, manganese and iron. Aluminium sheets are, whitish in colour and light in weight. They are highly, resistant to corrosion and abrasion., Aluminium is now widely used in the manufacture of, articles such as household appliances, refrigerator trays,, lighting fixtures, windows and also in the construction of, airplanes and in many electrical and transport industries., Tinned plate: Tinned plate is sheet iron coated with tin, to, protect it against rust. This is used for nearly all solder, work, as it is the easiest metal to join by soldering., This metal has a very bright silvery appearance and is used, in making roofs, food containers, dairy equipment, furnace, fittings, cans and pans etc., Lead sheets: Lead is very soft and heavy in weight., , Articles such as pans, buckets, furnaces, heating ducts,, cabinets, gutters etc. are made mainly from G.I.sheets., , Lead sheets are used for making the highly corrosive acid, tanks., , Stainless sheets: This is an alloy of steel with nickel,, chromium and other metals. It has good corrosive resistance and can be welded easily. Stainless steel used in, a sheet metal shop can be worked similar to galvanised, iron sheets, but is tougher than G.I. sheets. The cost of, stainless steel is very high., , When lead is coated on black iron sheets, they are called, Terne sheets. They are highly anti-corrosive and commonly used in preservation of chemicals., , 129, , Copyright Free Under CC BY Licence
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Indian Standard sheet sizes & strip sizes, Objectives:At the end of this lesson you shall be able to, • specify the Indian Standard sheet sizes, • specify the Indian Standard strip sizes, • calculate the weight of the steel sheet, and the measure of the strip., Indian Standard sheet sizes & strip sizes, As per Indian Standard are designated as ISSH received, by figures denoting length (mm) x width (mm) x thickness, (mm) of the sheet as per IS 1730 : 1989., Example, , Table 2 gives the weight of steel sheets of different, standard sizes., Exercise, Calculate the weight of the steel sheet given below., ISSH 1800x1200 x 1.40mm, , ISSH 3200 x 600 x 1.00, , _______________________________________________, , Where, , _______________________________________________, 3200 is the length of the sheet (mm), 600 is the width of the sheet (mm), 1.00 is the thickness of the sheet (mm), , 130, , P&M : Fitter - Related Theory for Exercise 1.3.43, , Copyright Free Under CC BY Licence
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TABLE 1, Standard Nominal Dimensions and Mass of Sheet, Size, Standard, mm x mm Nominal, Surface, Area, in m2, , Standard Nominal Thickness in mm, 0.40, , 0.50, , 0.63, , 0.80, , 0.90, , 1.00, , 1.12, , 1.25, , 1.40, , 1.60, , 1.80, , 1.90, , 2.00, , 1800 x 600, 750, 900, 950, 1000, 1100, 1200, 1250, 1400, 1500, , 1.08, 1.35, 1.62, 1.71, 1.80, 1.98, 2.16, 2.25, 2.52, 2.70, , 3.39, 4.24, 5.09, 5.37, 5.65, 6.22, 6.78, 7.07, 7.91, 8.48, , 4.24, 5.30, 6.35, 6.71, 7.06, 7.77, 8.48, 8.83, 9.90, 10.6, , 5.34, 6.67, 8.01, 8.45, 8.90, 9.79, 10.7, 11.1, 12.5, 13.4, , 6.78, 8.48, 10.2, 10.7, 11.3, 12.4, 13.6, 14.1, 15.8, 17.0, , 7.65, 9.54, 11.4, 12.1, 12.7, 14.0, 15.3, 15.9, 17.8, 19.1, , 8.47, 10.6, 12.7, 13.4, 14.2, 15.6, 17.0, 17.6, 19.8, 21.2, , 9.50, 11.9, 14.2, 15.0, 15.8, 17.4, 19.0, 19.8, 22.2, 23.8, , 10.6, 13.2, 15.9, 16.8, 17.7, 19.4, 21.2, 22.1, 24.7, 26.5, , 11.9, 14.8, 17.8, 18.8, 19.8, 21.8, 23.7, 24.7, 27.7, 29.7, , 13.6, 17.0, 20.3, 21.5, 22.6, 24.9, 27.1, 28.3, 31.7, 33.9, , 5.3, 19.1, 22.9, 24.2, 25.4, 28.0, 30.5, 31.8, 35.6, 38.2, , 16.1, 20.1, 24.2, 25.5, 26.8, 29.5, 32.2, 33.6, 37.6, 40.2, , 17.0, 21.2, 25.4, 26.8, 28.3, 31.1, 33.9, 35.3, 39.6, 42.4, , 2000 x 600, 750, 900, 950, 1000, 1100, 1200, 1250, 1400, 2500, , 1.20, 1.50, 1.80, 1.90, 2.00, 2.20, 2.40, 2.50, 2.80, 3.00, , 3.77, 4.71, 5.65, 5.97, 6.28, 6.91, 7.53, 7.85, 8.79, 9.42, , 4.71, 5.88, 7.06, 7.45, 7.85, 8.63, 9.42, 9.80, 11.0, 11.8, , 5.93, 7.42, 8.90, 9.39, 9.89, 10.9, 11.9, 12.4, 13.8, 14.8, , 7.53, 9.42, 11.3, 12.0, 12.6, 13.8, 15.1, 15.7, 17.6, 18.8, , 8.47, 10.6, 12.7, 13.4, 14.1, 15.5, 17.0, 17.7, 19.8, 21.2, , 9.42, 11.8, 14.1, 14.9, 15.7, 17.3, 18.8, 19.6, 22.0, 23.6, , 10.6, 13.2, 15.8, 16.8, 17.6, 19.3, 21.1, 22.0, 24.6, 26.4, , 11.8, 14.7, 17.7, 17.9, 19.6, 21.6, 23.6, 24.5, 27.5, 29.4, , 13.2, 16.5, 19.8, 20.8, 22.0, 24.2, 26.4, 27.5, 30.8, 33.0, , 15.1, 18.8, 22.6, 23.6, 25.1, 27.6, 30.1, 31.4, 35.2, 37.7, , 17.0, 21.2, 25.4, 26.8, 28.3, 31.1, 33.9, 35.3, 39.6, 42.2, , 17.9, 22.4, 26.8, 28.3, 29.8, 32.8, 35.8, 37.2, 41.8, 44.7, , 18.8, 23.6, 28.3, 29.8, 31.4, 34.5, 37.7, 39.2, 44.0, 47.1, , 2200 x 600, 750, 900, 950, 1000, 1100, 1200, 1250, 1400, 1500, , 1.32, 1.65, 1.98, 2.09, 2.20, 2.42, 2.64, 2.75, 3.08, 3.30, , 4.14, 5.18, 6.22, 6.56, 6.91, 7.60, 8.29, 8.63, 9.67, 10.4, , 5.18, 6.47, 7.77, 8.20, 8.63, 9.50, 10.4, 10.8, 12.1, 13.0, , 6.52, 8.16, 9.78, 10.3, 10.9, 12.0, 13.1, 13.6, 15.2, 16.3, , 8.28, 10.4, 12.4, 13.1, 13.8, 15.2, 16.6, 17.3, 19.3, 20.7, , 9.32, 11.7, 14.0, 14.8, 15.5, 17.1, 18.7, 19.4, 21.8, 23.3, , 10.4, 13.0, 15.5, 16.4, 17.3, 19.0, 20.7, 21.6, 24.2, 25.9, , 11.6, 14.5, 17.4, 18.4, 19.3, 21.3, 23.2, 24.2, 27.1, 29.0, , 13.0, 16.2, 19.4, 20.5, 21.6, 23.7, 25.9, 27.9, 30.2, 32.4, , 14.5, 18.1, 21.8, 23.0, 24.2, 26.6, 29.0, 30.2, 33.8, 36.3, , 16.6, 20.7, 24.9, 26.2, 27.6, 30.4, 33.2, 34.5, 38.7, 41.4, , 18.7, 23.3, 28.0, 29.5, 31.1, 34.2, 37.3, 38.9, 43.5, 46.6, , 19.7, 24.6, 29.5, 31.2, 32.8, 36.1, 39.4, 41.0, 45.9, 49.2, , 20.7, 25.9, 31.1, 32.8, 34.5, 38.0, 41.4, 43.2, 48.4, 51.8, , 2500 x 600, 750, 900, 950, 1000, 1100, 1200, 1250, 1400, 1500, , 1.50, 1.875, 2.25, 2.375, 2.50, 2.75, 3.00, 3.125, 3.50, 3.75, , 4.71, 5.88, 7.07, 7.45, 7.85, 8.63, 9.42, 9.81, 11.0, 11.8, , 5.88, 7.35, 8.83, 9.32, 9.80, 10.8, 11.8, 12.3, 13.7, 14.7, , 7.42, 9.26, 11.1, 11.7, 12.4, 13.6, 14.8, 15.5, 17.3, 18.5, , 9.42, 11.8, 14.1, 14.9, 15.7, 17.3, 18.8, 19.6, 22.0, 23.6, , 10.6, 13.2, 15.9, 16.8, 17.7, 19.4, 21.2, 22.1, 24.7, 26.5, , 11.8, 14.7, 17.7, 18.6, 19.6, 21.6, 23.6, 24.5, 27.5, 29.4, , 13.2, 16.5, 19.8, 20.9, 22.0, 24.2, 26.4, 27.5, 30.8, 33.0, , 14.7, 18.4, 22.1, 23.3, 24.5, 27.0, 29.4, 30.7, 34.3, 36.8, , 16.5, 20.6, 24.7, 26.1, 27.5, 30.2, 33.0, 34.3, 38.5, 41.2, , 18.8, 23.6, 28.3, 29.8, 31.4, 34.5, 37.7, 39.2, 44.0, 47.1, , 21.2, 26.5, 31.8, 33.6, 35.3, 38.9, 42.4, 44.2, 49.5, 53.0, , 22.4, 27.9, 33.6, 35.4, 37.2, 41.0, 44.7, 46.6, 52.2, 55.8, , 23.6, 29.4, 35.3, 37.2, 39.2, 43.2, 47.1, 49.1, 55.0, 58.9, , Based on the density of steel =7.85 g/cm2, For determining the mass of sheet above 2mm thickness, refer to IS1730:1989, , P&M : Fitter - Related Theory for Exercise 1.3.43, , Copyright Free Under CC BY Licence, , 131
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Indian Standard strip sizes, Indian Standard strips are designated as ISST followed by, width (mm) x thickness (mm) of the strip as per IS 1730 1989. (Fig.1), Example, ISST 1050 x 3.15: Where 1050 mm is the width of the, strip and 3.15mm is the thickness., , 132, , P&M : Fitter - Related Theory for Exercise 1.3.43, , Copyright Free Under CC BY Licence
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TABLE 2, Standard Nominal Dimensions and Mass of Strip, Thickness in mm, 1.60, , 1.80, , 2.00, , 2.24, , 2.50, , Width, in mm, , 2.80, , 3.15, , 3.55, , 4.00, , 4.50, , 5.0, , 6.0, , 8.0, , 10.0, , Mass * kg/m, , 100, 125, 160, , 1.25, 1.57, 2.01, , 1.41, 1.77, 2.26, , 1.57, 1.96, 2.51, , 1.76, 2.20, 2.81, , 1.96, 2.45, 3.14, , 2.20, 2.74, 3.52, , 2.47, 3.08, 3.95, , 2.79, 3.48, 4.46, , 3.14, 3.92, 5.02, , 3.53, 4.41, 5.65, , 3.92 4.71 6.28, 4.90 5.88 7.85, 6.28 7.53 10.0, , 7.85, 9.81, 12.6, , 200, 250, 320, , 2.51, 3.14, 4.02, , 2.82, 3.53, 4.52, , 3.14, 3.92, 5.02, , 3.52, 4.40, 5.62, , 3.92, 4.90, 6.28, , 4.39, 5.49, 7.05, , 4.94, 6.17, 7.90, , 5.58, 6.97, 8.92, , 6.28, 7.85, 10.0, , 7.06, 8.83, 11.3, , 7.84 9.42 12.6, 9.80 11.8 15.7, 12.5 15.1 20.0, , 15.7, 16.6, 25.1, , 400, 500, 650, , 5.02, 6.28, 8.16, , 5.65, 7.05, 9.17, , 6.28, 7.85, 10.2, , 7.04, 8.79, 11.4, , 7.85, 9.51, 12.7, , 8.78, 11.0, 14.3, , 9.88, 12.4, 16.1, , 11.1, 13.9, 18.1, , 12.6, 15.7, 20.4, , 14.1, 17.7, 23.0, , 15.7 18.8 25.1, 19.6 23.6 31.4, 25.5 30.6 40.8, , 31.4, 39.2, 51.0, , 800, 950, 1000, , 10.0, -, , 11.3, 13.4, -, , 12.6, 14.9, 15.7, , 14.1, 16.7, 17.6, , 15.7, 18.6, 19.6, , 17.6, 20.8, 22.0, , 19.8, 23.5, 24.7, , 22.3, 26.5, 27.9, , 25.1, 29.8, 31.4, , 28.3, 33.6, 35.3, , 31.4 37.7 50.2, 27.3 44.7 59.7, 39.2 47.1 62.8, , 62.8, 74.6, 78.5, , 1050, 1150, 1250, , -, , -, , 16.5, -, , 18.5, 20.2, -, , 20.6, 22.6, 24.5, , 23.3, 25.2, 27.5, , 26.0, 28.4, 30.9, , 29.2, 32.0, 34.8, , 33.0, 36.1, 39.2, , 37.1, 40.6, 44.2, , 41.2 49.5 65.9, 45.1 54.2 72.2, 49.1 58.9 78.5, , 82.4, 90.3, 98.1, , 1300, 1450, 1550, , -, , -, , -, , -, , -, , 28.6, -, , 32.1, 35.8, 383, , 36.2, 40.4, 43.2, , 40.8, 45.5, 48.7, , 45.9, 51.2, 54.7, , 51.0 61.2 81.6, 56.9 68.3 91.1, 60.8 73, 93.3, , 102, 114, 122, , Table 2 gives the weight in kg of a particular strip per metre, length., Exercise, Calculate the weight of a ISST 500 x 4 of 2 metres, Answer, _______________________________________________, , P&M : Fitter - Realted Theory for Exercise 1.3.43, , Copyright Free Under CC BY Licence, , 133
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Production & Manufacturing, Fitter - Sheet Metal, , Related Theory for Exercise 1.3.44, , Hand lever shears, Objectives: At the end of this lesson you shall be able to, • identify the hand lever shear, • state the principle of working, • state the constructional feature parts and their functions., Hand lever shear is a hand operated machine used to cut, sheet metal upto a thickness of 3 mm (10 SWG). When, the machine is mounted on the bench, it is called a hand, lever bench shear. It may also be mounted on the floor,, over a small platform. It is used for cutting along straight, lines and convex cutting of sheet metal. (Fig.1), , Fracture begins to run into the work hardened metal from, the point of contact of the cutting members. When these, fractures meet, the cutting members penetrate the whole, of the metal thickness. (Fig 5), , The lower blade of the hand lever shear is fixed (bottom, blade) and the upper blade is pivoted at an angle., The sheet being cut is prevented from tilting by a clamping, device, which can be adjusted to the thickness of the sheet., The knife cutting edge of the upper blade is curved so that, the opening angle at the point of cut remains constant., As the upper blade moves down on the sheet metal, the, metal is subjected to shearing force, which causes, deformation of the metal. (Fig 2 & 3) Increase in force, causes plastic deformation of metal., , Blade clearance is very important and should not exceed, 10 percent of the thickness to be cut and should suit the, particular material., Results of incorrect and correct setting of shear blade, are as follows., , After a certain amount of plastic deformation, the cutting, member begin to penetrate. The uncut metal work, harden, at the edge (Fig 4)., , 1 Excessive clearance causes a burr to form on the, underside of the sheet as shown in the (Fig 6)., 2 With no clearance, over strain is caused, the edge of, the sheet becomes flattened on the under sides as, shown in (Fig 7)., , 134, , Copyright Free Under CC BY Licence
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3 With the correct clearance, optimum shearing results, are obtained as shown in (Fig 8)., , Squaring shear, Objectives: At the end of this lesson you shall be able to, • state the function of the squaring shear, • describe the adjustments on the machine to control the length of the cut, • state the capacity of the machine, • explain the safety precautions to be observed when working on squaring shears., Squaring shear, Cutting sheet metals is called shearing., Squaring shears are used to cut large sheets into pieces, to handle sheets easily., Sheet metal can be cut by many simple machines., Squaring shears, (Fig 1) operated by foot, are used to cut, and trim large pieces of sheet metal. The size of the, machine is specified by the length of the bed and maximum, thickness of sheet it cuts. Front gauge and back gauge is, provided to adjust the length of cut. A back gauge controls, the length of the cut, when sheet is inserted from the front., A front gauge cut the sheet which is inserted from the back., Sheet holder is provided to hold the sheet firmly while it is, being cut. It is operated by sheet holder lever., The square gauge is adjustable and is kept at right angles, to the cutting blade. 18 gauge sheets or lighter can usually, be cut by squaring shear parts are as shown in Fig 1., The clearance between the blades (Fig 2) can be adjusted, by two adjusters. One adjuster shifts the table forward and, other shifts the table backward. (Fig 3), , Too much clearance causes a burr to form on the underside of the sheet (Fig 2a) with no clearance overstrain is, caused, the edges of the sheet becomes flattened on the, underside (Fig 2b). With the correct clearance optimum, shearing results are obtained (Fig 2c)., , P&M : Fitter - Related Theory for Exercise 1.3.44, , Copyright Free Under CC BY Licence, , 135
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Safety, Keep your fingers away from the cutting blade at all times., Never attempt to cut bar iron, wire or any heavy metal on, the squaring shears. This may nick the blade, which will, then make a notch in every edge you cut. For better, shearing results blade clearances and setting of blades are, shown in Fig 2 & 3., , Guillotine shears, Objectives: At the end of this lesson you shall be able to, • state the constructional features of guillotine shears, • explain working of guillotine shears, • explain setting procedures of squaring guide, front gauge and back gauge, • state the safety precautions to be followed while working on guillotine shears., Guillotine shears: On a treadle, guillotine, the bottom, cutting blade is fixed to the machine bed and the top blade, is operated by the treadle. The material to be cut is kept, on the bed and held in position by hand. The hold down, clamp comes into operation when the treadle is depressed., Figs 1&2 shows the treadle guillotine., , 136, , P&M : Fitter - Related Theory for Exercise 1.3.44, , Copyright Free Under CC BY Licence
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On some power operated guillotines, provision is given for, a single or continuous cutting action. If there is any doubt, in operating cutting control, check as follows., , – Align cutting mark to the edge of the bottom blade, , – Switch on guillotine, , Use of the squaring guide: Guillotines are commonly, fitted with a guide at one end of the bed, to enable sheets, to be cut without marking on the sheet., , – Depress pedal, – If the control is set for single cutting the cutting beam, is descent once for each depression of the pedal., – If the controls are set for continuous cutting the beam, will continue to raise and descend when pedal is, depressed., , – Depress pedal, ensuring that the other foot is away from, pedal bar., , Where the guide is fitted with a scale, a stop is fitted to, enable strips of a predetermined length to be cut accurately, as shown in Fig 4., , Power shear mechanism is shown in Fig 3., , Position sheets against guide for squaring the other end, over lap stops slightly as shown in Fig 5., , Safety, 1 All guillotines are very dangerous., 2 Place the guard in position before operating., 3 Never work from the back of a guillotine., , Safety: Wear protective gloves for handling sheet metal., Reverse sheet and reposition. Place same edge to guide., Pull sheet back against stop and depress pedal as shown, in Fig 6., , 4 Understand its safe operation fully, and the operation of, emergency switches should be known perfectly., 5 Gauges, if not being used, should be clear of the, material being cut., Cutting procedure: When cutting, already marked line, as shown in Fig 3., – Switch on power guillotine, – Place the sheet on bed of machine and slide between, blades, – Place the sheet on the bed of machine and slide, between blades, , Parallel setting of front gauge: The front gauge is used, when there is less overhang., , P&M : Fitter - Related Theory for Exercise 1.3.44, , Copyright Free Under CC BY Licence, , 137
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Before setting, check that the guillotine is switched off and, separated. (Power machine only), Keep wooden block under pedal as an added safe guard., Fit gauge bar by tee bolts of bar into slots in brackets., Procedure for tape measure (Fig 7), , Using scale on gauge brackets: Where a machine is, fitted with a graduated scale on the brackets, position, gauge bar to the required dimension and fully tighten the, nuts., Keep place supported against gauge bar as shown in Fig 9., – Slide the tape end between blades, – Edge of the tape is hooked against bottom blade, , Mark off plate to the size and shape. Set guide stop to give, correct length., , – Position gauge bar, keeping the bar parallel to the blade, – Tighten securing nuts slightly, – Adjust the gauge to required position by tapping lightly, by palm, – Adjust the gauge bar parallel to the blade and fully, tighten the nuts., When using a rule, – Place the rule between blades. Position required, dimension on the edge of bottom blade., – Place the gauge bar against end of the rule., – Position the bar parallel. Slightly tighten the nut and, adjust as shown in Fig 8., , Cut the sheet metal to the size and shape as per marking, , 138, , P&M : Fitter - Related Theory for Exercise 1.3.44, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Sheet Metal, , Related Theory for Exercise 1.3.45 - 1.3.47, , Sheet Metal Tools, Objectives: At the end of this lesson you shall be able to, • List out the measuring tools, marking tools and production tools used in the sheet metal work, Tools used in the sheet metal work are:, , 10 Surface plate, , I, , 11 Timper, , Measuring tools, , 1 Steel rule, , 12 Trammel, , 2 Outside micrometer, , 13 Marking table, , 3 Vernier caliper, , 14 Surface plate, , 4 Combination set, , III Production tools, , 5 Standard wire gauge, , 1 Snips, , 6 Radius gauge, , 2, , II Marking tools, , 3 Mallet, , 1 Tinman's square, , 4 Ball pane hammer, , 2 Scratch owl, , 5 Straight edge, , 3 Straight scriber, , 6 Templates, , 4 Bend scriber, , 7 Soldering iron, , 5 Punches, , 8 Blow lamp, , 6 Try square, , 9 Hand grooves, , 7 Wing compass, , 10 Stakes, , 8 Trammel, , 11 Surface plate, , 9 Jenny caliper, , 12 Riveting tools, dolly, staps etc., , Tin man's hammers, , 139, , Copyright Free Under CC BY Licence
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Measuring Tools, , Marking Tools Sheet Metal Worker, , 140, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Production Tools, , 142, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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144, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Machines and appliances tools, , 148, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Standard wire gauge, Objectives: At the end of this lesson you shall be able to, • state the use of the standard wire gauge, • state some important hints in using standard wire gauge, • state the metal thickness in mm for the given gauge numbers., The job drawing indicate only gauge or thickness of the, sheet to be used. Before starting the work identify the, correct thickness of the sheet. The thickness of the sheet, is measured with the help of the standard wire gauge., , Gauge number is stamped on one side of each slot and, on the other side, the decimal part of an inch is stamped, to show the thickness of the sheet and the diameter of the, wire., , The gauge consist of a disc shape smoothened steel metal, piece with numerous slots around the outside edge. These, slots are of various width and correspond to certain gauge, number. (Fig 1), , Thickness of the sheet is checked by inserting the edge, of the sheet in the appropriate slot of the standard wire, guage., Wire diameter is checked by inserting the wire only in the, slot, and not in the circle. (Fig 2), , Steel rule, Objectives: At the end of this lesson you shall be able to, • state the purpose of a steel rule, • state the precautions to be followed while using a steel rule., Engineer’s steel rules (Fig 1) are used to measure the, linear dimensions of workpieces. Steel rules are made of, spring steel or stainless steel. These rules are available, in lengths of 150 mm, 300 mm and 600 mm and 1000, mm. The reading accuracy of the steel rule is 0.5 mm., , For maintaining the accuracy of the steel rule, it is important, to see to it that its edges and surfaces are protected from, damage and rust., , For accurate reading it is necessary to read vertically to, avoid errors arising out of parallax. (Fig 2), , 150, , Do not place a steel rule with other cutting, tools., Apply a thin film of oil when not in use., , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Try square, Objectives: At the end of this lesson you shall be able to, • name the parts of a try-square, • state the uses of a try-square., The try-square (Fig 1) is a precision instrument which is, used to check the squareness of a surface and the flatness, of surfaces., , Clean the surface of the surface plate. Place the marking, media on the face of the surface plate. Keep the try square, blade on the surface and stock to the side of the surface, plate as shown in Fig 4. Scribe straight line., , The accuracy of measurement by a try-square is about, 0.002 mm per 10 mm length, which is accurate enough for, most workshop purpose. The try-square has a blade with, parallel surfaces. This blade is fixed to the stock at 900., Burr slot is provided on the stock at meeting point of blade, to accommodate the burr, if present on the component, to, avoid inaccuracy in measuring squareness., , Place the trysquare as shown in Fig 5 at the edge point of, marking and scribe straight line., , Uses: The try square is used to check the squareness of, a sheet. (Fig 2), , If the two marked lines are in one line as shown in Fig 6., Trysquare blade is 90° to the stock and it is correct., , To mark lines at 90° to the edges of a workpiece. (Fig 3), , If the two marked lines do not stand on the same line as, shown in Fig 7 means the blade is not 90° to the stock., , Try squares are specified according to the length of the, blade i.e. 100 mm, 150, 200 mm., To check the trueness of a trysquare., , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence, , 151
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Tinman’s “L” square, Objective : At the end of this lesson you shall be able to, • state the use of the Tinman’s “L” square., A Tinman’s “L” square is an “L” shaped piece of hardened, steel with graduation marks on the edges of the Tongue and, Body or blade (Fig.1). It is used for marking in the, perpendicular direction to any base line and to check the, perpendicularity., , The short arm of the “L” square is called the tongue and the, long arm is called the body or blade and the corner is called, the heel. The angle between the tongue and the body of the, “L” square is 90°., The size of the “L” square is specified by the length of the, body and the tongue., It is also called as Tinman’s square., , Straight edge, Objectives: At the end of this lesson you shall be able to, • state the uses of straight edge, • list the types of straight edge., Straight edge: Straight edge is a flat bar of steel., , Straight edges are available in two types., , It is used to mark straight lines on a sheet metal surface., , 1 Square straight edges, , Types (Fig 1), , 2 Bevel straight edge., Straight edges are available in 600 mm, 1 to 3 mtrs in, length. While marking with the help of a straight edge,, place the straight edge on the sheet and hold it by your, left hand., , 152, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Scriber/Scratch awl, Objectives: At the end of this lesson you shall be able to, • state the features of scribers, • list the types of scribers, • state the uses of a scriber., In layout work, it is necessary to scribe lines to indicate, the dimensions of the workpiece to be cut or folded., It is made out of high carbon steel about 3 to 5 mm dia. for, drawing clear lines on sheet metal, working point is ground, at one end angle of 10° to 20°. Scriber working point is, hardened and tempered., Scribers are available in different types and sizes., Types of scribers (Fig 1), – Straight scriber, – Bend scriber, – Scratch AWL, Scriber points are very sharp and they are to be handled, very carefully. Do not put the scriber in your pocket. Place, a cork on the point, when not in use to prevent accidents., , Types of marking punches, Objectives: At the end of this lesson you shall be able to, • state the different punches used in marking, • state the feature of each punch and its uses., Punches are used in order to make certain dimensional, features of the layout permanent. There are three types of, punches. They are, – Centre punch, – Prick punch, – Dot punch., Centre punch: The angle of the point is 900 in a centre, punch. The punch mark made by this is wide and not very, deep. This punch is used for locating holes. The wide punch, mark gives a good seating for starting the drill., (Fig 1), Prick punch: The angle of the prick punch is 300. This, punch is used for making light punch marks needed to, position dividers and trammels. The divider leg will get a, proper seating in the punch mark. (Fig 2), , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence, , 153
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Ball pane hammer, Objectives: At the end of this lesson you shall be able to, • state the construction of the ball pane hammer, • identify the parts of the ball pane hammer, • state the use of the ball pane hammer., A hammer consist of a head and a wooden handle., Hammer is used for light tapping and hard striking purposes, while punching, bending, straightening, chipping, forging,, riveting and planishing., Major parts of the hammer are shown in Fig 1., , The handle is fixed in the eye hole of the hammer at right, angle to the head., Face: The face is the striking portion. Slight convex is, given to avoid the digging of the edges., Peen: The peen is the other end of the head. It is used for, shaping, forming, riveting and bending. The peen is of, different shapes like, ball peen, cross peen and straight, peen as shown in (Fig 2). The face and peen are hardened., , The semi-spherical shape of the peen is suitable for riveting, and hollowing., The face is used for flattening and striking purposes., Specification: The hammers are specified by weight and, the shape of the peen. The weight varies from 125 grams, to 1500 grams. 250 grams ball peen hammer is used for, marking purpose., Before using a hammer, – Make sure that the handle is properly fitted., – Select a hammer with the correct weight, suitable for, the job., , Cheek: The cheek is the middle portion of the head. The, weight of the hammer is stamped here. This portion of the, hammer head is left soft., , – Check the head and the handle for any cracks., – Ensure that the face of the hammer is free from oil or, grease., , Eye hole: An eye hole is meant for fixing the handle. It is, shaped to fit the handle rigidly. The wedge is used to fix, the handle tight in the eye hole as shown in Fig 3 & 4., , Dividers, Objectives: At the end of this lesson you shall be able to, • state the uses of dividers, • state the specification of dividers, • state the important aspects to be considered in respect of divider points., Dividers are used for scribing arcs and circles, and stepping, of distances. (Figs 1,2&3), Dividers are available with firm joints and spring joints., (Fig 1 & 4) The measurements are set on the dividers with, a steel rule., , 154, , Constructional features: Spring dividers are made of tool, steel, sharp pointed legs. The points are hardened and, tempered. The legs are joined by a fulcrum roller and bow, spring. The distance should be adjusted between the, points with a ball headed screw and knurled nut. A peg is, provided on the top of the bow spring for easy handling., , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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The size of dividers ranges from 50 mm to 200 mm. The, distance from the point to the centre of the fulcrum roller, (pivot) is the size of the divider. (Fig 4), , For the correct location and seating of the divider legs,, prick punch marks of 30° are used., The two legs of the divider should always be of equal length., (Fig 5), , Dividers are specified by the type of their joints and length., The divider point should be kept sharp in order to produce, fine lines. Frequent sharpening with an oilstone is better, than sharpening by grinding., Sharpening by grinding will make the points soft., , Wing compass, Objectives: At the end of this lesson you shall be able to, • Name the parts of a wing compass, • state the uses of the wing compass, • state the specification of the wing compass, • state some important hints on the wing compass, • state the uses of a trammel beam., Wing compass is used for scribing circles, arcs and for, transforming and stepping off distances. (Fig 1,2 and 3), Compasses are available with (A) Firm joints (B) Wing (C), Spring joints and (D) Beam Compass or Trammel. (Fig 4), The measurements are set on the wing compass with a, steel rule., The sizes of a wing compass range between 50 mm to, 200 mm. The distance from the point to the centre of the, rivet is the size of the wing compass. (Fig 5), , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence, , 155
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For the correct location and seating of the wing compass, legs, 600 dot punch mark is indented. (Fig 6), The beam compass (or) Trammel is used to scribe a circle, or an arc with a large diameter which cannot be scribed, by a wing compass. (Fig 7), Parts of the wing compass are shown in Fig 8., The two legs of the compass should always be equal in, length. (Fig 9), Compass are specified by the type of the joints and length., When using spring type wing compass the measurement, once taken will not vary while marking., 156, , The compass point should be kept sharp, in order to, produce fine lines. Frequent sharpening with an oilstone, is better than sharpening by grinding. (Fig 10) Sharpening, by grinding will make the points soft., , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Straight snips, Objectives: At the end of this lesson you shall be able to, • state the uses of straight snips, • state the parts of straight snips, • state care and maintenance., A snip is also called a hand shear. It is used like a pair of, scissors to cut thin soft metal sheets. Snips are used to, cut sheet metal upto 20 S.W.G., , If the clearance is too large it cause unclean cut, chamfered, and jamming of workpiece as shown in Fig 3., , Uses of straight snips: The straight snips are used to cut, sheet metal along straight lines and outer sides of curves., Parts of straight snips are shown in Fig 1., , Types: There are two types of snips, 1 Straight snip, While cutting a sheet metal, blades are pressed against, the sheet, which causes shearing tension from both sides, as shown in Fig 2 and the cutting action takes place., , 2 Bent snip, Specification: Snips are specified by its overall length and, the shape of the blade. (snips are available in 150 mm,, 200mm, 300 and 400 mm overall length) Ex.200 mm,, straight snips., Safety: Avoid cutting wires and nails, if so the cutting edge, of the blade becomes damaged (Fig 4)., , Cutting edge of the blade and clearance: Clearance, between the blades should be free but without gap. For, straight snips, cutting angle is 87°., , Avoid cutting hard sheet metal, if so the blade becomes, blunt., Due to wear and tear, the cutting edge of the blades, becomes blunt. To resharpen the blade, the cutting angle, alone should be ground to an angle of 87° (Fig 5) and should, not grind the face of the cutting side of the blade. (Fig 6), , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence, , 157
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Bend snips, Objectives: At the end of this lesson you shall be able to, • state the use of the bend snips, • state the parts of the bend snips, • state the specification of the bend snips, • state types of shears and their application., The bend snips are used to cut the inside curved lines and, for trimming curved edges as shown in (Fig 1)., , Parts of the bend snips are shown in fig 2. The blades of, the bend snips are curved. (Fig 2), , Specification: Bend snips are specified by their overall, length. Bend snips are available in 150, 200, 300 and 400, mm length., Type of shears, 1 Tinman’s shears is sometimes called straight shears., , Uses, Tinmans shears (Fig.3): It is used for making straight, cuts and large external curves upto the thickness of 18, SWG. Cutting angle of a shears is 87º. The cross sectional, view of the cutting blades is shown in Fig 3. Never grind, the face of the blade., , Universal combination shears or Gilbow shears, (Fig 4), , Its blades are designed for universal cutting, straight line, or internal and external cutting of curves may be right hand, or left hand, easily identifiable as the top blade is either on, the right or the left. (Fig 5), , 2 Universal combination shears or Gilbow shears., 3 Pipe shears, 4 Scotch shears, 5 Block shears, 6 Rohdes shears, , 158, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Pipe shears (Fig.6): It is applied as bend shears in all, cases. Particularly it is used to time the edges of the, pipes., , Shearing force: To produce the maximum cutting force,, the hand must be kept far from the rivet and the metal, being cut must be kept close to the rivet., Hawk billed shears (Fig.10): It is used for the inside, cutting of an intricate work. The snips have narrow curved, blades that allow you to make sharp turns without bending, the metal., , Scotch shears (Fig.7): It is a shape as shown in the fig.9, its handles are formed as eye holes to give extra grip to, the hands. It is also used as Tinman's shears., , Block shears (Fig.8): One of the handle of the shear is, bent downwards as shown in the figure. The bending portion, should be fixed on the iron plates hole and the upper handle, will be held by the worker. It is used in mass production, purposes., , Aviation shears (Fig.11): It can be used for all kinds of, cutting. These are made with left, right or universal cutting, blades., , Bench shears (Fig.12): These are designed to have one, handle held in a vice or bench plate, while the other handle, is moved up and down., They can cut 16 gauge to 18 gauge thickness sheet metal., , Double cutting shears (Fig.13): These shears have three, blades used to cut around cylindrical objects, such as, cans and pipes. A single blade is pushed through the metal, to sheet to cut., , Rohdes shears: Its one handle is shorter in length as, compared with the other handle as shown in Fig.9., Electric portable shear (Fig.14): Electric shears are used, to cut corrugated metal sheets or a sheet metal of 18, gauge thickness or lighter sheet metals., The shear point can be inserted with a light hammer blow., Successive blows will drive the shear on a scribed line for, almost any shape like inner circles, zig zag, curvature, line easily. A strip of metal about 3"/32 (2.5 mm) wide is, removed in this shearing operations., The short handle is to be pressed by the right leg of the, worker and the other handle should be held by the right, hand. It is used to cut lengthy sheets., P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence, , 159
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Sheet metal mallets & hammers, Objectives: At the end of this lesson you shall be able to, • state the different types of mallets, • state the uses of mallets, • state the care and maintenance., Mallet is a shaping tool used for general purpose work, like flattening, bending and forming to required shape of, sheet metal., These are made of hard wood, When using any metal hammer for flattening the sheet, metal, the face of the hammer may damage or leave, impression on the sheet more than what is required for, the job. To avoid such damage and a impression, mallets, are used., Types (Fig 1), – Ordinary mallet, – Bossing mallet, – End-faked mallet, – Raw hide mallet., Ordinary mallet: Both the faces of the mallets are, provided the little convexity. If the face is not in convex, shape the edges of the mallet face will get frozen while, beating the job., Mallets are specified by the dia and the shape of the face., Mallets are available in 50 mm, 75 mm and 100 mm dia., , 160, , Avoid using the mallet as hammer for doing chipping and, to drive nails and work on the sharp corners., If so the face will get damaged and the mallet is liable to, break., , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Sheet metal hammers, Objectives: At the end of this lesson you shall be able to, • state the names of sheet metal hammers, • state the constructional features of sheet metal hammers, • state the uses of sheet metal hammers, • specify the sheet metal hammers, • state safety precautions while using the hammers., In the previous lessons, you learned about the Engineering, hammers such as Ball pane hammer, cross pane hammer, and straight pane hammer. Apart from these, there are, some special type of hammers used in sheet metal trade,, which are called sheet metal hammers., , Creasing hammer: Its both ends are sharpened and, cross to the handle. It is used to finish the wired edges,, false wiring edge and make corners of the sheet with the, help of a creasing stake. (Fig 3), , They are, 1 Setting hammer, 2 Riveting hammer, 3 Creasing hammer, 4 Stretching hammer, 5 Hollowing hammer, 6 Bullet hammer, Stretching hammer: Its shape is like a creasing hammer, but its pane ends are blended., , 7 Planishing hammer, 8 Peening hammer, Setting hammer: Its face is either round or square in, shape. Its pane is tapered from the eye hole and the other, side is straight to the handle. The tip of the pane is, rectangular in shape, and slightly convexed. It is used to, set up the seams, flaring the edge of the cylindrical jobs, and to set up the long channel also. Its face is used for, general purposes. (Fig 1), , It is used to stretch the sheets to increase the length of the, sheet. It is mostly used in raising operation. (Fig 4), , Hollowing hammer: Its both ends are shaped like ball, and well polished., , Riveting hammer: Riveting hammer’s face is round in, shape and the face is slightly convex. Its pane is long, tapered and straight to the handle vertically. The tip of the, pane is blended., , It is used to make hollowing operation on the metal sheet, and to remove the dents from the hollowed articles. This, hammer is mostly used for panel beating work. (Fig 5), , Riveting hammer is used to jump the rivet shanks and finish, the rivet heads. (Fig 2), , Bullet hammer: Its panes look like the hollowing hammer, but the body is longer than the hollowing hammer and, slightly bent. The pane ends are well polished and suitable, to work on deep portion., P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence, , 161
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It is used to draw deep hollowing where the hollowing, hammer cannot be used and also it is used to remove the, dents from the deep hollow portion. (Fig 6), , Safety precautions (Fig 9), , Planishing hammer: It’s one face is square and other is, round in shape and well polished. Its pane is slightly, convex. This hammer is heavy in weight., , – Always handle and face of the hammers should be free, from oil and grease., , It is used to give smooth surface finish to the jobs which are, hollowed and raised, and to planish the surface of the plain, sheets. (Fig 7), , Peening hammer: It’s face is round and slightly convex, and a pane is just like stretching hammer. This hammer, is used to peen polished impressions on the spinned, aluminium job and hollowed copper, brass house hold, vessels. (Fig 8), , Specification: The sheet metal hammers are specified by, the Type of pane and the weight of the hammer., , – Face of the hammers should be free from scratches,, dents, splits, burrs, chips etc., – The handle should be securely fitted to the head. The, wedge should be tight. (Fig 10), , – Hammers fitted with broken, cracked, splinted handles, should not be used. Replace the handles immediately., (Fig 11), , – Heads flying from poorly fitted or broken handle can, cause serious injuries., – Always use a piece of soft metal between the hammer, and the hard steel., – Never hit two hammer faces together because the faces, would split and the chips would fly dangerously., – Select the right hammer for that particular job., , Example, 1 lb Planishing hammer, , 162, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Soldering iron (soldering bit), Objectives: At the end of this lesson you shall be able to, • state the purpose of soldering iron, • describe constructional features of soldering iron, • state different types of copper bits and their uses., Soldering iron: The soldering iron is used to melt the, solder and heat metal that are joined together., Soldering irons are normally made of copper or copper, alloys. So they are also called as copper bits., Copper is the preferred material for soldering bit because, – it is a very good conductor of heat, – it has affinity for tin lead alloy, , Soldering bits are specified by the weight of the copper, head. For general soldering process, the shape of the head, is a square pyramid but for repetition, or awkward placed, joints, other shapes are designated., Point soldering copper bit: This is also called a square, pointed soldering iron. The edge is shaped to an angle on, four sides to form a pyramid. This is used for tacking and, soldering. (Fig 2), , – it is easy to maintain in serviceable condition, – it can be easily forged to the required shape., A soldering iron has the following parts. (Fig 1), , Electric soldering copper bit: The bit of the electric, soldering iron is heated by an element. This type is preferred,, if current is available because it maintains uniform heat., Electric soldering irons are available for different voltages and, are usually supplied with a number of interchangeable tips., They can be made quite small and are generally used on, electrical or radio assembly work. (Fig 3), , – Head (copper bit), – Shank, – Wooden handle, – Edge, SOLDERING COPPER BIT, Types of soldering copper bits: There are 7 types of, soldering copper bits in general use,, They are, – The pointed soldering copper bit., – The electric soldering copper bit., – The gas heated soldering copper bit., – Straight soldering copper bit., – Hatchet soldering copper bit., – Adjustable copper bit., – Handy soldering copper bit., The bits of soldering irons are made in various shapes and, sizes to suit the particular job. They should be large, enough to carry adequate heat to avoid too frequent, reheating and not too heavy to be awkward to manipulate., , Gas heated soldering copper bit: A gas heated soldering copper bit is heated by a gas flame which impinges on, the back of the head. High pressure gas is used and the, bits is large enough to have a good heat storage capacity., Liquified petroleum gas (LPG) flame is used extensively for, this purpose. Soldering kit normally includes many sizes, and shapes of bits which can be used to make most kinds, of soldering connections. (Fig 4), , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence, , 163
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Straight soldering copper bit: This type of soldering iron, is suitable for soldering the inside bottom of a round job., (Fig 5), , Hatchet soldering copper bit: This type of soldering iron, is very much suitable for soldering on flat position lap or, grooved joint outside round or square bottom. (Fig 6), , Handy soldering copper bit: It is like a hatchet type but, bigger in size than the hatchet. It is used for soldering, heavy gauge of metal. It should not be used for soldering, on light gauges of metal because additional heat will cause, the metal to buckle. (Fig 8), , Adjustable soldering copper bit: This type of soldering, iron is used for soldering where straight or hatchet bit, cannot be used for soldering. Adjustable soldering bit can, be adjusted in any position for soldering. (Fig 7), , Trammels, Objectives: At the end of this lesson you shall be able to, • state the uses of Trammels., Beam Trammels and taper measures: Trammel set is, used for striking lines at 90° to each other, and also for, measuring the distances accurately. It is a usual practice, for the craftsman to use a pair of trammel heads or ‘trams’, and any convenient beam such as a length of wooden, batten. The arrangement of the trammel for fine adjustment, for accurate marking out is shown in Fig 1., , The 900 angle lines i.e lines square with each other, may, be set out, with the aid of the beam trammel set or steel, tape as shown in Fig 2., The normal accuracy obtainable when marking out with, the dividers, and the trammels is within 0.15 mm of the true, dimension. Fig 3 show how the properties of a right angled, triangle can be used to set out a perpendicular line by, using trammel set., 164, , P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Groovers, Objectives: At the end of this exercise you shall be able to, • state what is groover, • state the size of the groovers, • state the uses and applications of groovers., Any seam in sheetmetal should be locked or closed property for effective functioning. Otherwise the joint will be a, failure., , The width of the groove is stamped on the tool body., Closing and locking, First the joint is held in position and then it is closed with, a mallet. (Fig 3), , What is a groover?, A groover is hand tool used for closing and locking of, seams in sheetmetal work. (Fig 1), , Then the groover is placed over the closed end of the joint., The groover is positioned at a very slight angle. The edge, of the joint acts as a guide to position the groover., The grooving operations are repeated for the other end of, the joint. (Fig 4 and 5)., , The end of the tool is recessed to fit over the lock making, the grooved seams. (Fig 2), , Sizes, Groovers are available in various sizes viz. 3mm, 4mm,, 5mm etc., Generally a groover 1.5mm wider than the width of the fold, is used., For thicker materials, a groover 3mm larger than the width, of the fold is used., , The joint is locked working along the joint in stages., The seam is tighted using a mallet or a light planishing, hammer., Failure to lock the joints in stages with the end of the, groover will result in bite marks along the joint., , Using too small a groover will mark the metal and prevent, locking., 165, P&M : Fitter - Related Theory for Exercise 1.3.45 -1.3.47, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Sheet Metal, , Related Theory for Exercise 1.3.48, , Stakes and their uses, Objectives: At the end of this lesson you shall be able to, • state what is a stake, • state the different types of stakes and their uses., Stakes are the sheet metal workers anvils used for bending, seaming or forming. They actually work as supporting, tools as well as forming tools., , Half moon stake (Fig 3): This stake has a sharp head in, the form of an arc of a circle, bevelled along one side. It is, used for turning up flanges on metal discs., , Stakes are made in different shapes and sizes to suit the, types of operations for which machines are not readily, available or readily adaptable., Some stakes are made of forged mild steel, faced with cast, steel. The better class stakes are made either of forged, steel or of cast steel., A stake used in sheet metal working consists of a head (or), a horn. (shank or body and heel) The shanks are designed, to fit into a tapered bench socket. (Fig 1), , Funnel stake (Fig 4): This stake is used when shaping and, seaming funnels and tapered articles., , Round bottom stake (Fig 1): It has a round and a concave, face head. It is used for hollowing the sheet., Hatchet stake (Fig 2): The hatchet stake has a sharp,, straight edge, bevelled along one side. It is very useful for, making sharp bends, folding the edges of sheet metal,, forming boxes and pans by hand., , Beak or Bick Iron stake (Fig 5): This stake has two horns,, one of which is tapered the other is a rectangular shaped, anvil. The thick tapered horn or beak is used when making, spouts and sharp tapered articles. The anvil may be used, for squaring corners, seaming and light riveting., Creasing Iron (Fig 6): This stake has two rectangular, shaped horns, one of which is plain. The other horn, contains a series of grooving slots of various sizes. The, grooves are used when ‘Sinking’ a bead on a straight edge, of a flat sheet. This is also used when making small, diameter tubes with thin gauge metal., Pipe stake or Square edge stake (Fig 7): This stake has, the horn and the shank. The horn is available in two types., one is with flat face as shown in (Fig 7A). Other one is with, curved face as shown in (Fig 7B) Flat face horn stake is, used to fold the edges, and to turn up straight edges. The, , 166, , Copyright Free Under CC BY Licence
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curved face horn stake is used to turn circular disc or curved, edges and to make knocked up joints., , Tinman’s Anvil (Fig 8): It is used for planishing all types, of flat shaped works. It is highly polished on its working, surface., Tinman’s Horse (Fig 9): This stake has two arms at its, both ends, one of which is usually cranked downwards for, clearance purpose. There is a square hole for the reception, of a wide variety of heads. (Fig 10), , The surface of the stake is important for the workmanship, of the finished article. Therefore, care must be taken to, avoid any damage to the surface of the stake when centre, punching or cutting with a cold chisel., Apart from these stakes, special types of stakes are also, available to suit different types of jobs., , P&M : Fitter - Related Theory for Exercise 1.3.48, , Copyright Free Under CC BY Licence, , 167
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Copper smith stake, Objectives: At the end of this lesson you shall be able to, • identify a copper smith stake, • state the constructional features of a copper smith stake, • state the uses of a copper smith stake, • state safety, care and maintenance while using a copper smith stake., It is not economical to have too many stakes for simple, operations in a sheet metal shop., Hence, an economical way of tooling is adopted and, designed by combining two edges of different cross, sections on a common head as in Fig 1. This stake is, called a copper smith stake or tinman’s anvil. It is a very, useful stake used in sheet metal work, due to its, constructional features., , 2 Do not use it for heavy work., 3 Do not spoil the surface of the stake by chiseling and, punching., 4 Do not spoil the edges by cutting wire or nails on the, edges of the stake., 5 Remove and keep it in its place after use., , This stake is used for flattening the surfaces of the sheet, metal, bending, flanging, finishing wired edges on both, straight and curved edges., These stakes are made of medium carbon steel and case, hardened., Safety care and maintenance, 1 Fix the stake firmly in the bench plate or stake holder, to avoid slipping and causing accidents., , Bottom round stake, Objectives: At the end of this lesson you shall be able to, • identify the Round Bottom Stake, • state the constructional features of this stake, • state the uses of this stake., Bottom round stake: This is a very common stake used, in a sheet metal shop. This stake is round in shape with, a flat face, slightly chamfered to avoid the cracking or, tearing of sheets while using it., It is used for turning edge on circular discs, seaming and, fixing bottom to cylindrical parts, making a paned down, joint at the bottom of the cylindrical parts. The tail is, designed to fit in the square slot made in the work bench, or stake holder., Do not cut wires or nails on the edge of the stake., This will spoil the edge and the same impression, will be formed on the sheet or the part formed on, it., , 168, , P&M : Fitter - Related Theory for Exercise 1.3.48, , Copyright Free Under CC BY Licence
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Stake holders, Objectives: At the end of this lesson you shall be able to, • name the different types of stake holders, • state the constructional features of stake holders, • state the uses of stake holders, • state safety, care and maintenance when using stake holders., There are three types of stake holders, 1 Bench plate, 2 Revolving bench plate, 3 Universal stake holder, Bench plate: Stakes are held in position while using them, by means of a plate which is fastened to the work bench, with bolts and nuts. These plates are called bench plates, or stake holders., These bench plates are made of cast iron and are rectangular, in shape as in Fig 1. The tapered holes are conveniently, arranged so that the shanks of the stakes may be fixed and, used in any convenient position. The smaller holes are, used to support the bench shears., , Revolving bench plate: Revolving bench plate consists, of a revolving plate with tapered holes to support the shanks, of the stakes while using them., This revolving bench plate can be held in any convenient, position by clamping it on to the work bench, with the, clamping provision provided on it as in Fig 2., Universal stake holder: Universal stake holder can be, clamped to any desired position on the work bench. So it, is preferred by most of the mechanics., This stake holder is designed with a set of stakes which, can be easily fixed on to the stake holder and hence it is, termed as universal stake holder set as shown in Fig 3., One stake may be replaced by another very quickly by, simply turning the swivel handle and replacing the stake., , When placing an order to purchase this type of stake holder, set, we should specify clearly the type of stakes to be, supplied along with the stake holder., Safety, care and maintenance:, – Fix the stake holder firmly on to the work bench., – Do not use it for very heavy work., – Do not overtighten the locking arrangements which may, spoil the threads on the device., – Do not place the unnecessary accessories on the work, table. Place only the required ones., – Avoid chiseling or punching on this stake holder., – Remove and keep it in its place after use., , P&M : Fitter - Related Theory for Exercise 1.3.48, , Copyright Free Under CC BY Licence, , 169
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Production & Manufacturing, Fitter - Sheet Metal, , Related Theory for Exercise 1.3.49, , Sheet metal seams, Objectives: At the end of this lesson you shall be able to, • state the types of seams., Introduction, In Sheet metal construction, mechanical seams are, employed when joining light and medium gauge metal, sheets. While fabricating sheet metal articles, the sheet, metal worker should be able to select the type of seam, that is best suited for the specific job., Types of seams, 1 Grooved seam : Grooved seam is most commonly, used for joining sheet metal. This seam consists of, two folded edges called locks as shown in Fig 1. The, edges are hooked together and locked with a hand, groover or a grooving machine., , 2 Pittsburgh seam: This seam is also called hammer, lock or hobolock. This seam is used as a longitudinal, corner seam for various types of pipes such as duct, work. The single lock is placed in a pocket lock and, then the flange is hammered over, step by step as, shown in Fig 2., , (A) Plain dovetail seam : It is used when joining a collar, to a flange without the use of solder, screws or rivet. It, is made by slitting the end of the collar and bending, every other tab as shown in Fig 5, , The advantage of the Pittsburgh seam is that the single, lock can be turned on a curve and the pocket lock can, be formed on a flat sheet and rolled to fit the curve as, shown in Fig 3. If roll forming machine is not available, in shop, Pittsburgh seam is formed on the brake., 3 Dovetail seam : This seam is an easy and convenient, method of joining flanges to collars. There are three, types of dovetail seams - plain dovetail, beaded dovetail, and the flange dovetail as shown in Fig 4., , The straight tabs are bent over the part to be joined and, the bent tabs act as stops. This seam may be made, water tight by soldering around the joint., , Dovetail seams are used mainly on round or elliptical, pipe and rarely on rectangular ducts., , 170, , Copyright Free Under CC BY Licence
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(B) Flange dovetail seam, This seam is used where neat appearance and strength, are important. The seam shown in Fig 6 is the assembly, of a flange type dovetail seam for a cylindrical pipe. It, is commonly used where pipes intersect with a metal, plate such as furnace flues, ceilings etc. Steps in, forming a flange dovetail seam are shown in Fig 6. First,, a flange is turned on the collar, next, slits are cut at, regular intervalsattheendofthesleeve and matching rivet, holes are drilled in the sleeve and the collar. The rivet, holes are aligned and the rivets are installed and finally, the tabs are hammered over to complete the seam., , The other type is used to fasten bottoms to cylindrically, shaped jobs such as pails, tanks etc., The steps in making this type of double seam is shown, in Fig 8, where A is turned on the machine. B is burred, on the burring machine. The bottom is snapped on the, body as in C and is peened down as in D. Finally the, seam is completed by using a mallet as in E. This seam, is called Bottom double seam or Knocked up seam., , If the seam is not turned up, as in D, the seam is called, paned down seam., 5 Butt seam, , (C) Beaded dovetail seam, This is similar to the plain dovetail seam, except a bead, is formed around one end of the cylinder by a beading, machine. This bead acts as the stop for the flange to, rest upon and the tabs are bent over to hold the flange, in the desired place., , This seam has two pieces butt together and soldered, as shown in Fig 9. Figure shows two types of butt, seams. One is flanged butt seam and the other one is, butt seam., , 4 Double seam, There are two types of double seams. One type is used, for making irregular fittings such as square elbows,, boxes, offsets, etc. This seam is used on corners and, can also be used as a longitudinal seam on small, square and rectangular ducts. A double edge is formed, and placed over the single edge and the seam is, completed step by step as shown in Fig 7., 6 Lap seam, The lap seam is made by lapping the edge of one piece, over the other piece and soldered as shown in Fig 10., Figure shows plain lap, sunk lap, inside lap and outside, lap seams., 7 Slip joint seam, This seam is used for a longitudinal corner seam as, shown in Fig 11., The assembly of the seam consists of a single lock A, and a double lock B. The single lock is slipped into the, double lock C to complete the seam., , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence, , 171
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For making pipes with a slip joint seam, proper care, should be taken to see that the corners of the metal are, squared and the edges are trimmed. The proper slip, joint is shown as A and improper as B in Fig 12. If the, edges are not trimmed, it will twist the pipe out of shape, and may cause the edges of the pipe to be uneven., , 172, , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence
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Locked grooved joint, Objectives: At the end of this lesson you shall be able to, • state the purpose of a joint, • state the use of the groover, • determine the allowance for the locked grooved joint, • know the type of shears, • know the uses of shears, • know about the shearing force, • know the blade clearance for optimum cutting., Locked grooved joint: Many methods are employed to, join and strengthen the pieces of a sheet metal. One of, the common joint is called locked grooved joint., This is usually done on straight lines. The workpieces to, be joined are made in the form of a hook, inserted and, locked using a groover., , Hand Groover: The hand groover is made up of cast steel, and is used to make external locked grooved joint., A groove is made at the bottom of this tool to the required, width and depth., This has a handle in square or hexagonal shape like chisel, to hold. This whole part is hardened and tempered. (Fig 4), , When they are interlocked and tightened only then it is, called a “grooved joint” (Fig 1)., , When the grooved joint is clinched down, making one side, plane using a groover is called a “Locked grooved joint”., (Fig 2), , The hand groover is specified according to the size of the, groove of the groover., External and internal locked grooved joints: This joint, is used to join the two ends of a sheet metal to form a, circular shape in longitudinal direction. When the seam, is formed outside as shown in Fig 3 then it is called ‘external, locked grooved joint’., , Locked grooved joint allowance: To arrive the size, (width) of the fold to suit a particular groover, subtract the, thickness by 3 times from the width of the groove. (Fig 5), , If the seam is formed using grooved mandrel then it is, called ‘Internal locked grooved joint’ (Fig 3), , For example, the width of the groover is 6 mm and the sheet, thickness is 0.5 mm,, Then the width of the fold, = 6 - (3 x 0.5), = 4.5 mm (See Fig 6)., , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence, , 173
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Stake joint, Objectives: At the end of this exercise you shall be able to, • State the applications of stake joint, • state the types of stake joints., Stake joint, , Straight stake joint, , It is one of the folded joint and is used in light articles such, as toys. It is also called as joint., , In this joint, clips and slots are in a line an the clips are, inserted directly, into the slots, folded and smashed in, opposite direction. (Fig 1), , In this type of joint, clips are cut on one pieces to be, jointed. Clips are inserted in slots and folded flat either in, one direction or alternate clips are folded in opposite direction. (Fig 1), , Zigzag stake joint, In this joint, clips are inserted in the slots and alternate, clips are folded in opposite direction. (Fig 2), , Types of stake joint, i, , Straight stake joint, , ii Zigzag stake joint, , Dovetail seam, Objectives: At the end of this exercise you shall be able to, • state a dovetail seam, • state the uses of a dovetail seam, • differentiate between a dovetail seam and a cramped joint., Dovetail seam is a very useful joint in sheetmetal fabrication work. The shape of the tabs cut like the tail of a dove., Hence it is called a dovetail seam. It is mostly used to join, the bottom to the body of sheet metal articles., This seam is very useful when joining a collar to a flange, without using solder or screws or rivets. This is done by, slitting the end of the collar at regular intervals and bending every other tabs as in Fig 1. The bent tabs act as, stoppers and the remaining tabs are bent over the plate to, be joined as in Fig 1. This joint may be made water tight, by soldering if required., , 174, , Flange dovetail seam (Fig 2): Fig 2 shows the assembly of a flange dovetail seam for cylindrical pipe. It is commonly used where pipes intersect witha flat metal plate, such as furnace constructional works. This is done where, extra strength and good apperance is required. First a, flange is turned on the collar Fig 2A. Next slits are cut at, regular intervals at the end of the sleeve and matching, rivet holes are drilled in the collar and sleeves Fig 2B. the, plate rests on the collar flange and sleeve is inserted into, the collar Fig 2C.the rivet holes are aligned and the assembly is riveted. Finally the tabs are bent over to complete the seam. Fig 2D., , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence
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Pittsburg lock, Objectives: At the end of this exercise you shall be able to, • define the pittsburg seam, • state the different types of pittsburg seams, • state the uses of pittsburg seams., Pittsburg lock is used in Duct work and is formed using, folding machine., It consists of a single lock or flanged section and a pocket, lock or pocket section. (Fig 1), , Single lock can be turned on the curve and pocket lock to, be formed on a flat sheet and then rolled to fit the curve., Example: W +W + 6.35mm, The width of the flanged edge is normally made slightly, less than the depth of the pocket., , Snap lock seam: Snap lock seam is as role formed seam, and is machine similar to pittsburgh lock seam. (Fig 3), , Usually, the allowances for the pocket is between 25 and30, and for the flange is between 6 to 8., , The allowance for this joint depends on the machine setting and is usually 25 to 30mm on the female lock setion, and 10mm allowance for the male section., , Fig2 shows the applications of pittsburgh lock the seam., , The male section has small wedge shaped projections,, punched at regular intervals on the flange as shown in, Fig 4. When this flange is pressed into female section,, the projections lock under a fold edge. This joint is a longitudinal seam in used in duct work. It is better than, Pittsbugh seam because it is heat in a apperances and, requires less time in fabrication., , Pittsburg losk seam applied to curveed work, Fig 3, When curved ducts like elbows are to be which incorporate the pittsburgh lock, the female section of the seam is, formed prior to curving., To make correct lock shape, a sheet metal strip spacer is, placed in between the first and second layers of the lock., The side is then curved t the shape in curving rolls. The, spacing strip is removed before assembling the component., P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence, , 175
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The standing seam (Fig 5): This standing seam is used, primarily to join panel section together. by allowing large, castings and wall cladding to be made with standard sized, sheets., , Strength and rigidly of the panel and the joint design is, simple and cost effetive as shown in Fig., The standing seam has a standing flange section which, may be from 25mm to 40mm depending on the length of, the seam and thickness of the material. Movement of the, seam is areested by button punching, riveting or bolting, the flange upstand 50mm from the end of the seam at, 150mm intervals. The standing seam can be prepared in a, bar folder or by manual folding., Cleat joints, Description and Allowances: Folded joints are the integral parts of an article and they all considered to be permanent fixtures., Cleats vary in application and design and commonly made, in a barfolding machine. Cleats which are of simle design, can be manually folded., It is a good practice to make a sample of the component, to be connected. Determine the size of the cleat., The drive slip: the drive slip is a simple design consisting, of a metal strip formed into a ‘C’ shaped section as shown, in Fig 6. The joint is made by driving the cleat over the, folds positioned at each end of the work to be joined. The, drive slip is mainly used to join lengths of duct work. the, joint is simply made by driving the cleat over the folds on, the ends of the jobs as shown in Fig 7., However, cleat joints consist of a folded cleat section which, inter locks with folds on articles to be joined and can be, dismantled, if necessary., , 176, , It is a good practice to insert a tongue into the end folds, of the abutting cleat. An alternate is to bend the tongue, and secure with blind the tongue and secure with blind, rivets as shown in Fig 8. A similar corner finish may be, done., Variation of duct end design will provide additional strength, as shown in Fig 9. In one example drive slip can be used, to connect channel folded ducts ends, which is giving the, appearance of a standing., Another example is the modification to a dive slip to include on upstand section., The Hemmed “S” slip: Used on ducts up to 600 mm in, width., Insert the ends of the duct sections into the open folds of, the “S” and secure with rivets at 100 mm intervals as shown, in Fig 10., , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence
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Standing “S” Slip: Used on ducts upto 1200 mm width in, made with a 35 mm upstand and 1500 mm wide with stand, of 50 mm as shown in Fig 11., , Pocket lock, For using a transverse joint on vertical duct, the cleat slips, over the upper edge of the bottom duct and the channel, part of the cleat takes the flanged end of the upper duct as, shown in fig 12, , The upstanding fold of the channel is dressed down by, hand, commonly at the time of installation., Mechanical fasteners, Introduction, A mechanical fastened joint is one in which two or more, sheet metal pieces are held together by a manufactured, device., P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence, , 177
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There are many variety of mechanical fasteners, available.The riveted joints in aircraft wing and the joints, bolted in air conditioning duct work provide two examples, as shown in Fig 13., , The large size of square or rectangular ducting tend to, drum when the air pressure passing through them varies., To overcome this drum, it isnecessary to keep aadequate, stiffening to the walls of ducts, it is necessary to keep, aadequate stiffening to the walls of ducts. This can be, achieved by the use of swaging but often a diamond break, iis used as shown in (Fig 15), , Use of angle stiffeners, Welded angle frames are used as the means of stiffening, and supporting rectangular ducts which are used for high, velocity systems. They also serve the purpose of joining, media when assembling sections together by bolting as, shown in (Fig 14), , 178, , Simple angle frames of welded construction may be used, for supporting and stiffening the open ends of tanks or, bins made from sheet metal. Two methods of attaching, the angle frames are shown in (Fig 16), , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence
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Folding and joining allowances, Objectives: At the end of this lesson you shall be able to, • state the necessity for providing allowances in sheet metal operations, • calculate the allowances for grooved joints, • calculate the allowances for dovetail joints, • calculate the allowances for paned down and knocked up joints., When making self secured joints or seams, it is necessary, to provide material for the preparation of the edges and, seams, the extra material is called an allowance., The allowance is necessary for maintaining the correct, size of the finished product and for improving the strength, at the joints of all edges., Allowance is also necessary for avoiding cracking or, warping, and for obtaining the required finish., This allowance depends upon the width of the folded edge, and the thickness of the metal., You may neglect the thickness of the metal for thinner, sheet of 0.4 mm or less., Allowance for grooved joints/ seams (Fig 1): If we fold, over the edges to width W and form the joint, the final, completed width of the joint G will be greater than W. It, can seen that the final width of the groove will have a, minimum value of W+ 3T, where T represents the metal, thickness., , The complete allowance for the Double Grooved Seam/, Joint will be four times the width of the folded edge plus, four times the thickness of the metal., Allowance for paned down and knocked-upjoints., The size of paned down and knocked-up joints is, determined by the width of the single folded edge., ‘P’ represents the size of the paned down joint (Fig 3) and, ‘K’ represents the size of the knocked-up joint. (Fig 4), , The allowance for a grooved seam is the width of the seam, + three times the thickness of the sheet, Allowance for double grooved seam/joint: It will be, seen from Fig.2 that the width of the capping strip is, equivalent of two times the width of the folded edge plus, four times the thickness of the metal size., Allowance for P = 2W + 2T, Allowance for K = 2W + 3T, , Edge stiffening by wiring, Objectives: At the end of this lesson you shall be able to, • state what is edge stiffening, • state what is the purpose of edge stiffening, • state methods of edge stiffening by wiring., Edge stiffening: Edge stiffening is the process by which, edges of the sheets are made stronger and rigid., Edge stiffening is done by, 1, 2, 3, 4, , Wiring, Hemming, Flanging, Curling, , 5 Beading, 6 Gutting, 7 Ribbing, Purpose of edge stiffening, 1 To give extra strength and rigidity to edges, to prevent, it from bending/buckling, damage during handling etc., 2 To avoid sharp edges for safe handling., , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence, , 179
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3 In addition, this adds to decorative appearance of the, sheet metal articles., Methods of edge stiffening by wiring, , In false wiring, sheet metal edges are wrapped around the, wire, after forming final shape, the wire is removed from, the edge to retain it hollow., If the edge of the sheet metal is straight, the edge formed, is called “straight wired edge”., , 1 Solid wiring, 2 False wiring, In solid wiring, sheet metal edges are wrapped around the, wire and wires are kept permanent in place. This is generally, called simple “Wiring”., , If the edge of the sheet metal is curved, the edge formed is, called “curved wired edge”., False wiring cannot be done on curved edges, , Wiring allowance, Objectives: At the end of this lesson you shall be able to, • state what is wiring allowance, • determine the wiring allowance., Wiring allowance is nothing but the amount of additional, length provided on sheet metal to wrap around the wire to, make a wired edge., Wiring allowance is deterined by the following formula., , If wiring allowance provided is more, then the correct shape, of the wire is not formed. If wiring allowance provided is, less, the gap is found at the inner side of the edge and, the wire can be seen., Generally, the length of the wire provided is slightly more, than the length of the edge. This is required to hold the, wire at ends, while forming the edge of the sheet metal, around the wire., , Wiring allowance = 2.5 x d+t, where, d=dia of wire, , Surplus wire is cut after the wired edge is finished., , t=thickness of sheet metal, , Making wired edge along a curved surface by hand process, Objectives: This shall help you to, • mark the wiring allowance at the curved edge, • make a wired edge along a curved surface by hand process, Mark the wiring allowance at the curved edge to be wired, using a gauge with sheet metal as shown in Fig 1., , Make a round ring from the given G.I.wire to the required, dia. (Fig 3), The joint of the wire should be opposite to the locked, grooved joint., Flange the edge to be wired using a hatchet stake and a, setting hammer, step by step upto 90º. (Fig 2) Then upset, the flange to its half the width and make curve on the, flange for wiring. (Fig 3), , 180, , Place the G.I. Wire ring on the flange. (Fig 4), , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence
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Complete the wiring using a creasing hammer. (Fig 5), Dress the wiring by using a half moon stake and a mallet., Redress the trueness of the cylindrical shape by a round, mandrel and a mallet., , False wiring, Objectives: At the end of this lesson you shall be able to, • state what is false wiring, • state advantages of false wiring, False wiring is one of the methods of edge stiffening in, which wired edge is formed and fially wire is removed from, the edge, to makethe edge hollow., Advantages of false wiring: In addition to advantages by, wiring, false wiring gives following advantages., , 2 Weight of the article is also reduced., In sheet metal articles like trunks, boxes etc,. wiring is, done only at the corners of the adjacent sides and the, remaining portion of the wired edge is kept hollow., This helps to maintain the sides in position., , 1 Cost of the article is reduced., , Hemming, Objectives : At the end of this lesson you shall be able to, • state the importance of hemming, • determine the hemming allowance., The sheet metal edges being thin are very unsafe while we, handle. They are like knife edge and can cause injuries., Therefore the edges should be made blunt by way of, making the edge folded to 180°. Also since the sheet metal, is very thin the edges will deflect due to low strength without, stiffness., For the above reasons the edges are hemmed(Fig 1) which, will ensure safety, retaining of shape, owning to the, stiffness and also enhance good appearance., , The folded edge will be more strong if it is not completely, flattened and a hollow channel is made., Usually the hemming allowance will be 3 to 4 times the, thickness of the sheet to be hemmed, subject to a, minimum of 4 M M., If the hemming widdth is more, wrinkles are formed at the, hemmed edges., A hemmed box is shown in Fig 2 gives good appearance,, safe and strong edge., , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence, , 181
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Double hemming by Hand Process, Objectives : At the end of this lesson you shall be able to, • state the purpose of double hemming, • give the hemming allowance for the first and second folds., Double hemming is done by folding twice. This give more, strength, when compared to single hemming. This is done, on various sheet metal articles which in square, rectangular, objects like trays. (Fig1 & Fig 2), While doing double hemming, care must be taken making, second fold. Angle of folding should be grade increased, throughout the length of the fold., , Edge Stiffening, Objectives : At the end of this lesson you shall be able to, • make a single hemming on a curved edge using anvil stake and setting hammer., Mark the hemming allowance on the formed body using a, marking template., Fix the anvil stake on to the vice or bench plate., Hold the workpiece such that the marked line coincides, with the edge of the stake approximately inclined an angle, of 10° as shown in Fig 1., , Strike and rotate the workpiece gradually along the marked, line to form a small flange using a setting hammer. (Fig 2), Gradually increase the angle of inclination while forming, range as shown in Fig 3., Finish the hemmed edge on a round mandrel stake by a, let (Fig 4), Press the disturbed body of the cyclinder to a round shape, using round mandrel stake and a mallet, Check the cylindrical body for roundness and the marketing allowance for flanging., Fix the copper smith stake in the benchvice or bench plate, firmly., 182, , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence
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Position the cylinder as in Figure 1 and strike the metal, using the flat face of the finishing hammer., Rotate the body of the cylinder by one hand., Strike with finishing hammer to increase the angle of bending gradually as in (Fig 7) till the flange is bent to 90°, , Mark the flanging allowance as guideline on the stake as, in Fig 5, , Hold the cylinder such that the marked line on the cylinder for flanging, coincides with the straight edge of the, stake. (Fig 6), , P&M : Fitter - Related Theory for Exercise 1.3.49, , Copyright Free Under CC BY Licence, , 183
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Production & Manufacturing, Fitter - Sheet Metal, , Related Theory for Exercise 1.3.50-51, , Solders, Objectives: At the end of this lesson you shall be able to, • define a solder, • state the types of solders, • state the constituents of soft and hard solders., Solder is a bonding filler metal used in soldering process., Pure metals or alloys are used as solders. Solders are, applied in the form of wires, sticks ingots, rods, threads,, tapes, formed sections, powder, pastes etc., , are alloys of the materials tin, lead, antimony, copper,, cadmium and zinc and are used for soldering heavy (thick), and light metals. Table shows different compositions of, solder and their application., In the composition of soft solder, tin is always, stated first., , Types of solders, There are two types of solders., – Soft solder, , WARNING, , – Hard solder, , For cooking utensils, do not use solder containing lead., This could cause poisoning. Use pure tin only., , Soft solders: Soft solders are alloys of tin and lead in, varying proportions. They are called soft solders because, of their comparatively low melting point. One distinguishes, between soft solder whose melting points are 450ºC and, hard solders whose melting points lie above 450ºC. These, , Hard solders: These are alloys of copper, tin, silver, zinc,, cadmium and phosphorus and are used for soldering heavy, metals., , Table 1, Sl.No., , Types of solder, , Tin, , Lead, , Application, , 1, , Common solder, , 50, , 50, , General sheet metal, applications, , 2, , Fine solder, , 60, , 40, , Because of quick setting, properties and higher strength,, , 3, , Fine solder, , 70, , 30, , they are used for copper water, tanks, heaters and general, electrical work., , 4, , Coarse solder, , 40, , 60, , Used on galvanised iron sheets, , 5, , Extra fine solder, , 66, , 34, , Soldering brass, copper and, jewellery, , 6, , Eutectic alloy, , 63, , 37, , Similar to fine solder, , Soldering flux, Objectives: At the end of this lesson you shall be able to, • state the functions of soldering fluxes, • state the criteria for the selection of fluxes, • distinguish between corrosive and non-corrosive fluxes, • state different types of fluxes and their applications., All metal rust to some extent, when exposed to the, atmosphere because of oxidation. The layer of the rust, must be removed before soldering. For this, a chemical, compound applied to the joint is called flux., , Functions of the fluxes, 1 Flues removes axides from the soldering surface it, prevents corrosion, 2 It forms a liquid cover over the workpiece and prevents, further oxidation., , 184, , Copyright Free Under CC BY Licence
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3 It helps molten solder to flow easily in the required, place by lowering the surface tension of the molten, solder., Selection of flux: The following criterias are important, for selecting a flux., – Working temperature of the solder, – Soldering process, – Material to be joined, Different types of fluxes: Flux can be classified as (1), Inorganic or Corrosive (Active) & (2) Organic or noncorrosive (Passive)., Inorganic fluxes are acidic and chemically active and, remove oxides by chemically dissolving them. They are, applied by brush directly on to the surface to be soldered, and should be washed immediately after the soldering, operation is completed., Organic fluxes are chemically inactive. These fluxes coat, the surface of the metals to be joined and exclude the air, from the surface, to avoid further oxidation. They are applied, only to the metal surfaces which have been previously, cleaned, by mechanical abrasion. They are in the form of, lump, powder, paste or liquid., Different types of fluxes, (A) Inorganic fluxes, 1 Hydrochloric acid: Concentrated hydrochloric acid is, a liquid which fumes when it comes into contact with, air. After mixing with water 2 or 3 times the quantity of, the acid, it is used as dilute hydrochloric acid. Hydrochloric acid combines with zinc forming zinc chloride, and acts as a flux. So it cannot be used as a flux for, sheet metals other than zinc iron or galvanised sheets., This is also known as muriatic acid., , 2 Zinc chloride: Zinc chloride is produced by adding, small pieces of clean zinc to hydrochloric acid. It gives, off hydrogen gas and heat after a vigorous bubbling, action, thus producing zinc chloride. The zinc chloride is prepared in heat resisting glass beakers in small, quantities. (Fig 1), Zinc chlorides are known as killed spirits. It is mainly, used for soldering copper, brass and tin sheets., 3 Ammonium chloride or Sal-Ammoniac: It is a solid, white crystalline substance used when soldering copper, brass, iron and steel. It is used in the form of powder or mixed with water. It is also used as a cleaning, agent in dipping solution., 4 Phosphoric acid: It is mainly used as flux for stainless steel. It is extremely reactive. It is stored in plastic containers because it attacks glass., (B) Organic fluxes, 1 Resin: It is an amber coloured substance extracted, from pine tree sap. It is available in paste or powder, form., Resin is used for soldering copper, brass, bronze, tin, plate, cadmium, nickel, silver and some alloys of these, metals. This is used extensively for electrical soldering work., 2 Tallow: It is a form of animal fat. It is used when soldering lead, brass and pewter., , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence, , 185
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Table 1, The following Table shows the nature and type of flux used in soldering., Metal to, be soldered, , Inorganic flux, , Organic flux, , Aluminium, Aluminium-bronze, , Remarks, , Commercially prepared, flux and solder required, , Brass, , Killed spirits, Sal-ammoniac, , Resin, Tallow, , Commercial flux available, , Cadmium, , Killed spirits, , Resin, , Commercial flux available, , Copper, , Killed spirits, Sal-ammoniac, , Resin, , Commercial flux available, , Gold, Lead, , Resin, Killed spirits, , Tallow, Resin, , Monel, Nickel, , Commercial flux required, Killed spirits, , Silver, , Resin, , Commercial flux available, , Resin, , Stainless steel, , Phosphoric acid, , Commercial flux available, , Steel, , Killed spirits, , Tin, , Killed spirits, , Tin-bronze, , Killed spirits, , Resin, , Tin-zinc, , Killed spirits, , Resin, , Zinc, , Muriatic acid, , Commercial flux available, , Tin-lead, , Soft soldering, Objectives: At the end of this lesson you shall be able to, • explain soft soldering process, • state the melting characteristics of soft solders, • state the essential features of the soldering technique, • explain the importance of the attitude of the bit, • state the importance of movement of the bit in soldering, • state the characteristics of the soldered seams to be observed while inspection., Soft soldering involves the process, – preparing the workpiece., – select the correct soft solder., – preparing the soldering iron., – select and apply suitable flux., – heat the soldering iron bit and the workpiece to the, correct temperature., – manipulating the soldering iron on the workpiece skillfully, as shown in Fig 1., – complete the job to a satisfactory standard., 186, , Melting characteristics of soft solders: The eutectic, alloy of tin lead solder is a mixture of 63% tin and 37% lead., 63/37 solder melts at 1830C and is the lowest melting point, of all combinations in the alloy series as shown in Fig 2., Soldering Techniques: The following features are essential to do soldering., – Correct joint design, – Preparation of the joint, – Selection of the solder, , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence
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– Selection and preparation of the soldering iron., – Copper bit heating, – Soldering bit manipulation, – Cleaning after soldering, – Inspection of the seam., , The pattern of the bit movement ensures successful heating, of the solder deposited, when the point of the bit covering, the joint opening penetrate through the lap as shown in, figure 4, , Flux residues and stains should be removed from the, seam, to keep clean dry surfaces for paint finishes., Inspection of the seam: A soldered seam should have, the following characteristics., – The solder has penetrated the lapped surfaces., Attitude of the bit: The soldering iron bit should be placed, in a position that enables sufficient heat and solder to flow, into the joint., The angle between a working face of the bit and the joint, surface should be filled with a pocket of solder.(Fig 3), Any variation of this angle will control the amount of heat, and solder which is transferred onto the lapped surfaces., Contact between the molten solder and the joint opening, is essential for the penetration of the solder into the joint, as shown in figure., , – The joint gap is sealed with a neat smooth fillet of the, solder., – The upper surfaces of the seam must be smooth, thin, coating of solder, with tidy solder margins with uniform, width., Visual inspection is good to rectify the faults of the solder., However, physical testing for air or water tight seams is, specified often. Leaks, detected by the tests are corrected, by re-cleaning, re-fluxing and re-soldering of the faulty area, in the soldered seam., , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence, , 187
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Process of soft soldering and hard soldering, Objectives: At the end of this exercise you shall be able to, • define ‘soldering’, • state the different types of soldering processes, • state the different types of solder and their applications, • state the different types of soldering bits and their uses., Soldering method: There are different methods of joining, metallic sheets. Soldering is one of them., , The process of joining metals using tin lead solders which, melt below 420°C is known as soft soldering., , Soldering is the process by which metallic materials are, joined with the help of another liquified metal (solder). The, melting point of the solder is lower than that of the materials being joined., , The process of joining metals using hard solders consisting of copper, zinc, cadmium and silver which melt above, 600° is known as hard soldering, , The solder wets the base material without melting it., Soldering should not be done on joints subjected to heat, and vibrations and where more strength is required., Soldering can be classed as soft soldering and hard soldering., , Brazing is a hard soldering process used to join copper, brass and most ferrous metals., The bonding filler metal usually consists of copper and, zinc alloys. Silver brazing or silver soldering is a process, used to join steel, copper, bronze and brass and precious, metals like gold and silver., The bonding filler metal consists of silver, copper and zinc, tin alloys., , Factors considered while soldering, Objectives: At the end of this exercise you shall be able to, • follow the conditions for proper define ‘soldering’, • state the different types of soldering processes., Soldering is joining two metal parts with a solder, i.e. a, third metal that has a lower melting point., , 4 Proper amount of heat must be applied. If you folds, these conditions, you could get a good solder joint., , Before soldering the following conditions must be met., , Cleanliness: Solder will never stick to a dirty, oil or exide, coated surface. Begineers often ignore this simple point, the metal is dirty. Clean it with a liquid cleaner. If it is a, annealed sheet remove the oxide with an abrasive and, clean it until the surface is bright., , 1 The metal must be clean, 2 The correct soldering device must be used and it must, be in good condition, 3 The correct solder and flux or soldering agent must be, chosen., , A bright metal, such as copper, can be coated with even, though you cannot see it. This oxide can be removed with, any fine avrasive., , Successful soldering, Objective : At the end of this lesson you shall be able to, • follow the hints for successful soldering., Hints for successful soldering, You should always wear safety glasses to avoid possible, injury to the eyes., Sheet metal must be cleaned with a file, wire brush, steel, wool strip, or emery cloth., Be sure that the pieces to be soldered fit closely together,, for a strong joint., , Hold the soldering iron in one hand, placing its widest tinned, face flat against the surface to be soldered., When soldering iron is held incorrectly, the point of the, soldering iron touches only a portion of the area to be, soldered, this is referred to as “skimming” the joint and, results in a weak joint., , Soldering flux must be applied by a swab or brush only to, the surfaces on which molten solder is to be applied., , Apply the wire solder beneath the edge of the iron and, nearest to the work. Move the soldering iron slowly along, the work making sure that the solder melts, spreads and, penetrates properly., , Hold the pieces to be soldered firmly to prevent their, movement., , Solder as much surfaces as possible without re-heating, the soldering iron or changing to another iron., , 188, , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence
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A temperature capable of merely melting the solder is not, sufficient enough, heat must be transmitted by the soldering, iron to the workpiece to quickly raise the temperature of, the metals to the solder melting temperature., , A soldering iron that is too small, often causes difficulty., Do not breathe any smoke from the sal ammoniac block, as it is a toxic gas and is dangerous., , It is this step in soldering that beginners often fail to, understand and remember., , Sweating of sweat soldering, Objective : At the end of this lesson you shall be able to, • explain the process of sweating., Sweating or Sweat soldering is a process, in which two or, more surfaces are soldered one on the top of the other, without allowing the solder to be seen after assembly., In sweating, metal surfaces to be joined are tinned first,, then placed on above the other and heated together. While, heating, the solder melts and flows to join the overlapped, surfaces., , Sweating process is applied in body repairing works in, which the damaged surface is sweat soldered with a piece, of metal called patch. This process is also applied in, rectifying leakages of water tanks and fuel tanks., , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence, , 189
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Soldered Joint, Objectives: At the end of this lesson you shall be able to, • state the types of the soldered joints, • state the points to be considered for correct joint design., Types of soldered joints: Sheet metal components are, joined together by soldered joints. In many cases, the, edges are joined by sheet metal mechanical joints and, then soldered to make the joint stronger and leak proof., , Sheet metal joints both lapped and folded, are suitable for, silver soldering application as shown in Fig.4, , Fig 1 shows soldered lap joints., , Silver solder effects the union of lapped joints and seals the, beam openings of the interlocking folded joints., Correct joint design: Sheet metal joints with overlapping, surfaces are ideal for joining or sealing with solder. Close, fitting of lapped surfaces are essential for the flow of molten, solder into the joint by capillary action., Fig 2 shows soldered seams., , Joint design suitable for silver brazing or soldering mainly, depends on the type of assembly and its intended use., Maximum strength can be achieved by observing the, following conditions., – A suitable filler alloy must be used., Component metal is of major consideration., – Joint clearances should be minimum., Close fitting surfaces helps capillary flow and gaps, between 0.05 and 0.13 mm should be used., – The solder must contact lapped surface sufficiently., , Fig 3 shows soldered joint on round shaped parts., , Lap width is commonly made 2 to 10 times the, component metal thickness. In case of unequal, thickness, the lap size is based on the thinner materials., – Workpieces must be firmly supported., It is essential to prevent the movement for the control of, the solder application, alignment and accuracy of the, component assembly., , 190, , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence
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Dipping solution, Objectives: At the end of this lesson you shall be able to, • state the use of the dipping solution, • state the constituents of the dipping solution., It is used to dissolve oxides from solder coated faces of, the copper bit before applying it to the workpiece., , 3 Adding commercial flux with zinc chloride or, ammonium chloride as active ingredients to water., , It is made of, , A mixture of approximately one part of active component, and four parts of water is satisfactory as the acidity of the, solution should not be strong., , 1 Dissolving sal-ammoniac powder in water., 2 Dilute zinc-chloride with water., , Safety precautions in soldering, Objective : At the end of this lesson you shall be able to, • follow safety precautions in soldering to avoid injuries/accidents., Safety precautions followed while soldering, , 5 Wear safety goggles when using acids for cleaning., , 1 Wear safety glasses to protect your eyes from solder, splattering and flux., , 6 When making acid solution, always pour acid into water, slowly., , 2 Be careful while storing hot soldering irons after use to, avoid burns., , 7 Never pour water into the acid., , 3 Wash your hands thoroughly after using soft solder, because it is poisonous., , 9 Wear goggles and gloves while handling corrosive flux., , 8 All inorganic fluxes are poisonous., , 4 Tin the soldering iron in a well ventilated area to exhaust, fumes coming out while soldering., , Fluxes types and description, Objectives : At the end of this lesson you shall be able to, • explain flux and its function, • describe the types of fluxes and their storage., Flux is a fusible (easily melted) chemical compound to be, applied before and during welding to prevent unwanted, chemical action during welding and thus making the, welding operation easier., The fuctions of fluxes : To dissolve oxides and to prevent, impurities and other inclusions that could affect the weld, quality., Fluxes help the flow of filler metal into very small gap, between the metals being joined., Fluxes act as cleaning agents to dissolve and remove and, clean the metal for welding from dirt and other impurities., Fluxes are available in the form of paste,, powder and liquid., The method of application of flux is shown in Fig. 1, Storing of fluxes; where the flux is in the form of a coating, on the filler rod, protect carefully at all times against, damage and dampness. Fig 2., Seal flux tin lids when storing especially for long periods, (Fig 2 ), , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence, , 191
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Though the inner reducing envelope of an oxy-acetylene, flame offers protection to the weld metal, it is necessary to, use a flux in most cases.Fluxes used during welding not, protect the weldment from oxidation but also from a slag, which floats up and allows clean weld metal, to be, deposited. After the completion of welding, flux residues, should be cleaned., Removal of flux residues: After welding or brazing is, over, it is essential to remove the flux residues. Fluxes in, general are chemically active. Therefore, flux residues, if, not properly removed, may lead to corrosion of parent metal, and weld deposit., Some hints for removal of flux residues are given below:, -, , Aluminium and aluminium alloys- As soon as, possible after welding, wash the joints in warm water, and brush vigorously. when conditions allow, follow up, by a rapid dip in a 5 percent solution of nitric acid; wash, again,using hot water to assist drying., , -, , When containers, such as fuel tanks, have been welded, and parts are inaccessible for the hot water scrubbing, method, use a solution of nitric and hydrofluoric acids.To, each 5.0 litres of water add 400 ml of nitric acid (specific, gravity 1.42) followed by 33ml of hydrofluoric acid (40, percent strength). The solution used at room temperature, will generally completely remove the flux residue in 10, minutes, producing a clean uniformly etched surface,, free from stains. Following this treatment the parts, should be rinsed with cold water and finished with a hot, water rinse. The time of immersion in hot water should, not exceed three minutes, otherwise staining may, result; after this washing with hot water the parts should, be dried. It is essential when using this treatment that, rubber gloves be worn by the operator and the acid, solution should preferably be contained in an aluminium, vessel., , -, , Magnesium alloys-Wash in water followed quickly by, standard chromating. Acid chromate bath is, recommended., , -, , Copper and brass- Wash in boiling water followed by, brushing.Where possible, a 2 percent solution of nitric, or sulphuric acid is preferred to help in removing the, glassy slag, followed by a hot water wash., , -, , Stainless steel- Treat in boiling 5 percent caustic soda, soultion, followed by washing in hot water. Alternatively,, use a de-scaling solution of equal volume of hydrochloric, acid and water to which is added 5 percent of the total, volume of nitric acid with 0.2 percent of total volume of, a suitable restrainer., , -, , Cast iron- Residues may be removed easily by a, chipping hammer or wire brush., , -, , Silver brazing -The flux residue can be easily removed, by soaking brazed components in hot water, followed, by wire brushing. In difficult cases the work piece, should be immersed in 5 to 10 percent sulphuric acid, solution for a period of 2 to 5 minutes, followed by hot, water rinsing and wire brushing., , Types of spelters and fluxes used in brazing, Objectives: At the end of this lesson you shall be able to, • state the types of spelter and flux used in brazing, • state the composition of spelter and its melting point., Brazing is essentially similar to soldering but it gives a, much stronger joint than soldering. The principal differences is the use of a harder filler material, commercially, known as spelter which fuses at some temperature above, red heat, but below the melting temperature of the parts to, be joined. Filler materials used in this process may be, divided into two classes. Copper base alloys and silver, base alloys. There are a number of different alloys in each, class, but brass (Copper and Zinc) sometimes with upto, 20% tin are mostly used mainly for brazing the ferrous, metals. Silver alloys (Silver and Copper or Silver and, , 192, , Copper and Zinc) having a melting point range of 600 to, 8500C are suitable for brazing any metals capable of being, brazed. They are giving a clean finish and a strong ductile, joint. Spelters are commonly made according to the, thickness of sheets., After brazing, the joint must be hammered to check the, leakages and to remove flux. Mostly and commonly used, flux is “Borax” for ferrous and non-ferrous metals. It removes, rust and prevents atmospheric effect, when brazing, operation is going on., , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence
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COMPOSITION OF SPELTER AND MELTING POINTS, Common, metals, , Copper, %, , Zinc, %, , Silver, %, , Melting, temperatures, , Sl., No., , Types of, spelters, , 1, , Copper +, Zinc, Base, spelter, , Common, , 60, , 40, , NIL, , 8500C, , Hard brazing, on copper, sheets and, non-ferrous, , 2, , -do-, , Ferrous, metals, , 80, , 20, , NIL, , 6000C, , Brass sheet, thick, , 3, , -do-, , brass, , 30, , 70, , NIL, , 4000C, , Brass sheet, thin, , 4, , Silver, solder, , Gold, , 10, , 10, , 80%, , 3500C, , It is used for, gold ornaments, brazing, , Uses, , Silver brazing of copper pipes by gas, Objectives: At the end of this lesson you shall be able to, • explain the term silver brazing, • state the various applications of silver brazing., Applications, , Silver brazing (Fig 1), , This low temperature brazing alloy is suitable for the, following., Joining electrical parts requiring high electrical conductivity. (Fig 2), , A low temperature brazing method., Also called by other names such as:- Silver soldering, Hard, soldering., Its temperature range is 600°C to 850°C., Silver-brazing filler rods are composed of copper and silver, with a small percentage of Zinc, Cadmium and Nickel., Silver content may vary from 40 to 60%., , Food handling and processing equipment. (Stainless steel)., Economy in brazing operation requiring a low temperature,, thin layer, quick and complete penetration., Joining of thin sheets and close fitted joints in steel,, copper, brass, bronze, nickel alloys and nickel-silver, alloys., Brazing tungsten carbide tips to ROCK DRILLS, MILLING, CUTTERS, CUTTING and SHAPING TOOLS. (Fig 3), , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence, , 193
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Joining dissimilar metals and jewellery making works., There is economy in the brazing operation as it requires, only low temperature and a thin layer of deposition. There, is quick and complete penetration in this method of joining., , Blow lamp, Objectives: At the end of this lesson you shall be able to, • state the constructional feature of blow lamp, • identify the parts of blow lamp, • describe the operation of blow lamp., In blow lamp (Fig 1) the kerosene is pressurized to pass, through pre-heated tubes, thus becoming vaporised. The, kerosene vapour continues through a jet to mix with a air, and when ignited directed through a nozzle, producing a, forceful flame., , The flame within the housing provides the heat to maintain, vaporisation of the kerosene. The free flame at the nozzle, outlet is used to heat the soldering bit., Blow lamp is a portable heating appliance used as a direct, source of heat for soldering irons or other parts to be, soldered. Fig 1 shows parts of blow lamp., It has an tank made of brass, filler cap is fitted at its top to, fill kerosene. A pressure relief valve is connected to the, mouth to switch ON/OFF and control the flame., Priming trough is provided for filling methylated spirit for, lighting the blow lamp. Set of nozzle is provided to direct, the kerosene vapour to produce forceful flame. Burner, housing is mounted on support brackets on which soldering, iron is placed for heating as shown in figure., Pump is provided to pressurise the kerosene in the tank., , Portable hand forge with blower, Objectives: At the end of this lesson you shall be able to, • state the purpsoe of hand forge, • describe the constructional feature of hand forge, • state the fuel used in hand forge., Hand forge: It is used for heating the soldering bit., It is made of mild steel plates and angles. It is generally, round in shape. the hand blower is attached to it for air, supply., A pefforated plate is fixed at the bottom to remove burnt, residuals., The fuel zone is built up with fire bricks and coated with, the mixture of clay and sand, providing space at the centre, for fuel. (Fig 1), The fuel used for firing is mainly charcoal. The charcoal, is prepared from hard wood., , 194, , P&M : Fitter - Related Theory for Exercise 1.3.50 -1.3.51, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter- Sheet Metal Worker, , Related Theory for Exercise 1.3.52 - 55, , Rivets and riveting, Objectives : At the end of this lesson you shall be able to, • define rivets, • specify rivets, • name the materials from which rivets are made, • name the different types of rivets and state their uses., Rivets are used to join together two or more sheets of metal, permanently. In sheet metal work riveting is done where:, brazing is not suitable,, the structure changes owing to welding heat,, , Rivets are cylindrical rods having heads of various, shapes.They are used for assembling the parts of a, workpiece together., Parts of the rivet (Fig 1), , the distartion due to welding cannot be easily removed etc., Specification of rivets, Rivets are specified by their length, material, size and, shape of head., Rivets, There are various kinds of rivets as shown in Fig 1. Snap, head rivets, countersink rivets and thin bevelhead rivets are, widely used in sheet metal work., Material:, Rivets are made of ductile materials like low carbon sheet, (mild steel), brass, copper, yellow brass, aluminium are, their alloys., The length of the rivets ‘L” is indicated by the shank length., (Fig 1), , Shape of head, The shape of the rivet head is to be selected according to, the intended use of the workpiece to be riveted., Diameter, The diameter is to be selected depending on the required, strength., Length, Length is to be selected depending upon the thickness of, the components to be riveted., Types and uses, Snap head (Fig 2), , 195, , Copyright Free Under CC BY Licence
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It is the most commonly used form, and it gives a very, strong joint., , Countersunk head (Fig 5), It is used where projection of the rivet head is to be avoided., , Pan head (Fig 3), It is used in heavy structural work where the strength of rivet, is very important., , Bifurcated rivet (Fig 6), The shape of the head is shown in the figure and the, bifurcated portion is used for fastening light parts- tin, plates, leather, plastics, etc., , Conical head (Fig 4), It is generally used in light assembly where riveting is done, by hand hammering., , Riveted Joint, Objectives: At the end of this exercise you shall be able to, • define ‘riveting’, • state the use of riveting, • name the materials from which rivets are made, • name the different types of rivets used in sheet metal work, • follow rules and formulas for riveting process, • Name the orienting process, Riveting: Riveting is one of the methods of making permanent joints of two or more pieces (Metal strips). It is, customary to use rivets of the same metal as that of the, parts that are being joined together., Uses: Rivets are used for joining metal sheets and plates, in fabrication work, such as bridges, ship building, games,, structural steel work., , Selection of rivet size: The diameter of the rivet is calculated by using the formula D= (21/2 to 3) xT where T is, total thickness, Lapping allowance: Normally in sheet metal trade, we, will use the following formula that is Three times of the dia, of rivet +2 times the sheet thickness on thin sheets, , Types of rivets:, , Pitch allowance: Three or four times the diameter of rivet, +Sheet thickness 1 time, , Tinman’s rivet, , The shank length is given by, , Flat head rivet, , Length :- L= T+D where T is the Sheet thickness and D, is the diameter of the rivet., , Round head rivet, , Normally Tinman’s rivets are designated by numbers., , Countersunk head rivet, Each rivet consists of a head and cylindrical body., Sizes of rivets: Sizes of rivets are determined by the, diameter and length of the shank., 196, , Thickness of sheet 14, 16, 18,20,22,25, Dia of rivet 22, 24,26, 27, 28, 30, , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence
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Sketch, , Hole diameter, , Draw a straight line of 1.25” and add sheet thickness, for total distance find out centre, and draw, a semi circle with spring divider, Draw a perpendicular line projecting the line upto semi, circle the distance is taken as a dia of rivet., Rivet hole size and clearance: A rivet hole should be, formed a little bigger than the nominal diameter of the, rivet.The hole diameter will be bigger than the rivet shank, nominal diameter by 0.2 to 0.3 mm for cold riveting and by, 0.5 to 1.5mm for high temperature (Red) for hot riveting, process., Working condition, Cold Riveting, Hot Riveting Process, , 2.2 3.2 4.2, 8.5 11 13 16.5, 5.3 6.3, Annealing of rivet: Riveting is usually performed in the, normal temperature when the rivet diameter is less than, 6mm. To prevent the breakage and failure of rivets and to, faciltates the operation, rivets are used in the normal temperature. Rivets are annealed in the temperature of 650° C, to 700°C and allow them to cool slowly. Generaly M.S, Rivets are heated in furnaces uniformly. Aluminium rivets, are used without annealing. High strength aluminium alloyed Rivets in the Duralumin group are heated to 480°C, adn 500°C and, coded in water. Generally Electric furnaces are used for heating the rivets., Method of riveting: Riveting may be done by hand or to, machine. While riveting by hand it can be done with a ball, pane hammer and a rivet set., , Rivet Nominal, 2 3 4 5 -6, , Rivet set: The shallow, cup shape hole is used to draw, the sheet and the rivet together . The output on the side, allows the slug to drop out., , 8 10 12 15 15 to 40, diameter (MM), , The cup strap is used for forming the rivet head. The set, selected should have a hole slightly larger than diameter, of the rivet., , Tolerance (DA), 0.2+ + 0.2 +0.5-0.2+0.5-0.2, 0.2++0.2, , Spacing of rivets: The space of distance from the edge, of the metal to the centre of any rivet should be atleast the, twice diameter of the rivet to avoid tearing., , Bigger than nominal diameter, by 1.5 to 2.0 mm plates., , The maximum distance should never exceed 24 time thickness of the sheet. Otherwise buckling will take place., , Rivets proportions, Objectives: At the end of this lesson you shall be able to, • determine the hole sizes for different diameters of rivets, • choose the rivet diameters according to the thickness of the plates/sheets, • calculate the length and rivet interference for different diameter rivets and plate sizes., Riveting: In order to produce efficient and good quality, riveted joints the following aspects are important., The size of the hole drilled for inserting the rivets., The diameter of the rivet in proportion to the thickness of the, plates/sheets to be joined., The length of the rivet according to the type of the rivet and, the thickness of the plates/sheets., The size of the rivet and hole: The size of the hole to be, drilled is according to the diameter of the rivet used., , D.Min = T, to D.Max = 2T, The actual value used will depend upon the actual joint, features and service conditions., The size of the hole has to be slightly larger than the, nominal diameter of the rivet. (Table 1), For hot working, rivets will have holes with more clearance, than for cold working., , A formula generally used for determining the diameter a, solid rivet is, , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence, , 197
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TABLE 1, Hole diameter for rivets, Rivet nominal dia, , 2, , 3, , 4, , 5, , 6, , 8, , 10, , 12, , 15, , 15-40, , Hole dia, , 2.2, , 3.2, , 4.2, , 5.3, , 6.3, , 8.5 11, , 18, , 16.5, , Holes larger than, the nominal dia by, 1.5 to 2.0 mm, , Length of rivets: The length of a rivet is the shank length., This will vary according to the thickness of the plates to be, riveted and the type of the rivet head.(Fig 1 & 2), , Rivet interference: The length required to form the head, in riveting is called rivet interference., When forming a round head (Fig 3) the interference x is, given as, x = d x (1.3, - 1.6), where x = rivet interference (mm), d = rivet diameter (mm), , Therefore, the length of the rivet (L mm) to form a round, head when the total thickness of the piled plates is T mm, will be, as given below., L = T + d (1.3 ~ 1.6), When forming a flat head (Fig 4) the length of the rivet, (L’mm) will be as given below., L’ = T + d (0.8 ~ 1.2), , A formula generally used in the shop floor is length of snaphead rivets., L = T + 1.5D, Length of countersunk head rivets L = T + 0.6 D, L = shank length, T = total thickness of the number of plates used, D = rivet diameter, D1 = hole diameter, , When he appropriate values of the rivet diameter and the, length for the plate thickness are found out, choose the, rivets with the standard size close to the calculated values., , Types of riveted joints, Objectives: At the end of this lesson you shall be able to, • state the different types of riveted joints, • state the features of different types of riveted joints, • distinguish between chain riveting and zigzag riveting., In construction and fabrication work different types of, riveted joints are made., The commonly used joints are:, , – double riveted lap joint, – single strap butt joint, – double strap butt joint, , – single riveted lap joint, 198, , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence
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Single riveted lap joint: This is the simplest and most, commonly used type of joint. This joint is useful for joining, both thick and thin plates. In this, the plates to be joined, are overlapped at the ends and single row of rivets is placed, in the middle of the lap.(Fig 1), , Double riveted lap joint: This type of joint will have two, rows of rivets. The overlap is large enough to accommodate, two rows of rivets.(Fig 2), , Double riveted (Zigzag) lap joint: This provides a, stronger joint than a single lap joint. The rivets are placed, either in a square formation or in a triangular formation. The, square formation of rivet placement is called CHAIN riveting. The triangular formation of rivet placement is called, zigzag riveting.(Fig 3), , Single strap butt joint: This method is used in situations, where the edges of the components are to be joined by, riveting.(Fig 4), , A separate piece of metal called STRAP is used to hold the, edges of the components together., This joint is also used for joining the edges of components, together. This is stronger than the single strap butt joint., This joint has two cover plates placed on either side of the, components to be assembled.(Fig 5), , When single or double straps are used for riveted butt, joints, the arrangement of rivets may be:, – Single riveted i.e one row on either side of the butt., – double or triple riveted with chain or zigzag formation., (Fig 6), , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence, , 199
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Layout the spacing of rivet holes in chain riveting, Objectives: At the end of this exercise you shall be able to, • lay out the spacing of rivet holes to make chain riveting, Fig1 shows the layout of the spacing of rivets holes in, chain riveting, In chain riveting, square formation of rivets is formed in, placement of rivets., , Zig Zag Riveting, objectives: At the end of this exercise you shall be able to, • State what is zigzag riveting, • draw the layout for the spacing of rivets in zigzag riveting, Zig zag riveting is one type of layout of rivet spacing in, veted joint, Zig zag riveting, triangular formation of rivets is formed in, placement of rivets., Layout of spacing for zigzag riveting is shown in Fig 1., , Spacing of rivets in joints, Objectives: At the end of this lesson you shall be able to, • determine the distance between the rivet and the edge of the joint, • state the effect on the joints when the rivets are too close or too far from the edge, • determine the pitch of rivets in joints, • state the effect of too close and too far a pitch of rivets in joints., The spacing of the rivet holes depends upon the job. Given, below is a general approach in determining this., Distance from the edge to the centre of the, rivet.(Fig 1), , 200, , The space or distance from the edge of the metal to the, centre of any rivet should be atleast twice the diameter of, the rivet., The purpose of this is to prevent the splitting of the edges., The maximum distance from the edge should not be more, than ten times the thickness of the plate.(Fig 2), , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence
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Too much distance from the edge will lead to GAPING., (Fig 3), , Too closely spaced rivets will tear the metal along the, centre line of the rivets., Pitch of rivet: The minimum distance between rivets, should be three times the diameter of the rivet. (3D) (Fig 4), , The maximum distance between the rivets should exceed, twenty four times the thickness of the metal.(Fig 6), Too far a pitch will allow the sheet/plate to buckle between, the rivets., , The distance will help to drive the rivets without, interference.(Fig 5), , Tubular bifurcated and metal piercing rivets, Objectives: At the end of this lesson you shall be able to, • state different types of tubular and bifurcated rivets, • state the constructional features of them, • state the application of them., Tubular and bifurcated rivets: These rivets are used in, low tension joints or for joining softer materials to sheet, metals, as given hereunder., Semi-Tubular rivets: This rivet has straight hole or, tapered hole at the end of the shank. The depth of the hole, must not exceed 1.12 time shank diameter as shown in, Fig 1. The rivet shank should extend upto the full thickness, of the joint, with the hollow portion set to give correct, upsetting., Full Tubular rivets: This rivet has a hole greater than, 1.12D and is designed for use, where the rivets is desired, to punch the rivet through soft materials as shown in Fig 3., , Insulated rivets: This rivet is semi-tubular and under the, rivet head, it is covered with thick nylon as shown in Fig 2., The main application of these rivets are in electrical, assemblies, where the rivet needs to be insulated from the, workpiece, and also for air tight or water tight joints., P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence, , 201
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Bifurcated or Split rivet: The bifurcated or split rivet is, machined to produce two prongs at the shank end to pierce, soft materials as shown in Fig 4., , Metal piercing rivets (Fig 5): These rivets pierce their own, holes into the sheet metal joints., These are similar to solid rivets and have good tension and, shear characteristics. These are economical as they, produce their own holes and are used in mass production, applications., Semi-tubular metal piercing rivets: These rivets are, designed to use as punches to penetrate fully or partially, on both pieces of the metal., If the rivet fully penetrates the metal, it then completes the, joint as shown in Fig . When the rivet partially penetrates, the metal, the tail of the rivet forms a sealed joint., Total sheet metal base thickness upto 2.5 mm can be used, for semi-tubular metal piercing rivets., Metal-piercing solid rivets: In this countersunk solid, rivets can be driven into the sheet steel upto 3.2 mm total, thickness with out the need of a hole. Penetration by the, rivet, counter sinking and clinching the rivet against an, upsetting tool, are completed in a single stroke. The, counter sunk head produces a flashed hole which improves, joint shear strength., Expansion of the rivet end on the other side of the, workpiece, prevents pull out., , Blind rivet or pop rivet, Objectives: At the end of this lesson you shall be able to, • state the types of blind rivets, their parts and application, • state the blind riveting equipment, • state the steps in riveting the blind rivets., Blind rivets are designed to allow them to be installed in, joints which are accessible from one side only. However,, for many reasons including simplicity and good appearance, they are used for joints from both sides are accessible. Prepared holes are required for blind riveting., The parts of the rivet is shown in the Fig 1. The mandrel, portion is used for assembly purposes only and after use,, it is either totally or partially discorded. (Fig 2), Blind riveting equipment: The equipment used for blind, rivets are blind rivet pliers, lazy tongs, lever hand tools,, 202, , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence
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pneumatic and hydraulic magazine feed and semi-automatic fasteners as shown in Fig 3., , Types of Blind or Pop rivets: In setting a blind rivet, the, body of the rivet is inserted into a hole and the mandrel is, pulled deforming the tail which pulls and fixes the joint, together. Blind rivets are available in many types and, systems. Some of these are given here-under., Plugged break stem: After the rivet tail has been deformed by the action of the mandrel, the mandrel stem, breaks, leaving the head behind forming a plug as shown, in Fig 4., , Externally threaded blind rivets: This rivet is a conventional pull mandrel blind rivet. When the rivet is set, the, head section protrudes providing a metric thread stud into, which a nut can be fastened. (Fig 7), , Collapsible shank: The tail or shank of this rivet is, designed to deform into three segments. (Fig 8) It spreads, the clamp up load over a wide area, making it suitable for, assemblies having bigger size hole and also to prevent pull, out in soft materials., Open break stem: It is similar to the break stem, but the, head breaks off and falls out after deforming the tail, leaving, the hollow body open. (Fig 5), Sealed: The sealed type rivet is hollow cored with a closed, blind end and is used where a water or pressure tight rivet, is essential. (Fig 6), , Flush break high strength: This blind rivet in 3 to 6 mm, diameters has a mandrel with specially designed head that, breaks off flush with the top of the rivet. (Fig 9), , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence, , 203
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Riveting blind rivet, Riveting steps, , Repetition blind riveting systems: Rivet is loaded onto, a mandrel which is placed into a pneumatic setting tool with, a rivet in the ready position. This rivet is inserted into a, preformed hole, the tool trigger is actuated, drawing the, mandrel through the rivet, expanding the rivet tail. Sequence of rivet setting is shown in Fig 10., , 1 Select a rivet for the correct size of dia and length., 2 Drill a hole to the recommended diameter., 3 Open the riveting tool and insert the rivet stem into the, tool nozzle., 4 Place the rivet body into the preformed hole., 5 Squeeze the rivet tool handles together to set the rivet,, at the correct point of tension, the rivet stem will break., 6 When the rivet stem has broken, remove the tool from, the job. Allow the tool to open fully to eject the spent, rivet stem. (Fig 12), , Drive pin rivets: Drive pin rivets consist of a hollow body, and a pin. In the manufactured condition itself, the pin, projects from the rivet head. A hammer blow forces the rivet, into the prepared hole, the pin expands the rivet and, spreads pre-slotted shank prongs. (Fig 11), , 204, , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence
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Lazy tong, Objectives: At the end of this lesson you shall be able to, • state what is a lazy tong, • state parts and mechanism of a lazy tong, • state the operating instructions., Lazy tong is a hand operated tool, used for setting 1/8", 5/, 32" and 3/16" diameter standard open type blind rivets. It, is important to use the correct nosepiece for the diameter, of the rivet to be placed, to ensure the best performance of, the tool. The parts list is shown in the figure and all parts, are fully interchangeable., Description of mechanism: The mandrel gripping mechanism consists of a set of jaws (6) fitted into the jaw case (5), and screwed on to the power coupling assembly. The jaws, are kept in the forward position by the jaw pusher (12) AND, JAW PUSHER SPRING (11)., The lazy tong mechanism is connected to the power, coupling in such a way that the operation of the handle (8), which draws the jaws, is gripping the rivet mandrel, thus, setting the rivet., Operating instructions: Check that the suitable nosepiece, is fitted to the tool and firmly screwed into the threads., \When the mandrel breaks, the rivet is set., , Hand-riveting tools, Objectives: At the end of this exercise you shall be able to, • name the different hand-riveting tools, • state the uses of different hand -riveting tools, Rivet set, , Dolly, , It is used for bringing the sheet metal closely together, after inserting the rivet in the hole, , It is used to support the head of the rivet which is already, formed and also to prevent damage to the shape of the, rivet head (Fig 1), , This is required while riveting thin plates or sheet with, small rivets (Fig 1), , Rivet snap, It is used to form the final shape of the rivet during riveting., Rivet snaps are available to match the different shapes of, rivet heads (Fig 2), Combined rivet set: This is a tool which can be used for, setting and forming the head (Fig 3), Hand riveter: This has a lever mechanism which exerts, pressure between the jaws when the handle is pressed., This is useful for riveting copper or aluminium rivets. Interchangeable anvils can be provided.(Fig 4), Pop riveter: This is used for riveting pop rivets by hand., The trigger mechanism squeezes the rivet and separates, the mandrel of the rivet. In this method as the mandrel is, being separated from the rivet, the head is formed on the, other end (Fig 5), , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence, , 205
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Fullering tool, It is used for pressing the surface of the edge of the plate, (Fig 8) Fullering helps to make fluid-tight joints., , Reasons for faulty rivetting, The holes on the plate are not in line (Fig 9), , The shank or body of the rivet is not perpendicular to the, plate before riveting (Fig 10), , Drift, It is used to align the holes to be riveted. (Fig 6), Caulking tool, It is used for closing down the edges of the plates and, heads of the rivets to form a metal-to-metal joint (Fig 7), , 206, , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence
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Too much or too little allowance has been given. (Fig 11, and 12), , Improper joining of plates.(Fig 14) plates are not brought, closely together using rivet set., , Burrs between plates and in drilled holes.(Fig 15 and 16), , Rivet head is not centered with the shank or body of the, rivet (Fig 13), , Caulking and fullering, Objectives: At the end of this lesson you shall be able to, • state the purpose of caulking and fullering, • distinguish between caulking and fullering processes., Caulking: Caulking is an operation of closing down the, edges of the plates and heads of the rivets to form a metalto-metal joint.(Fig 1), , The whole surface of the edge of the first plate is tightly, pressed on the second plate., A better fluid-tight joint is achieved by fullering., The edge of the rivet head is tightly pressed and expanded, on the plate by a caulking tool which looks like a fattened, cold chisel., Fullering: Fullering is an operation of pressing the whole, surface of the edge of the plate. It is done by a fullering, tool.(Fig 2), When the caulking tool is about as thick as the plate, it is, called a fullering tool., , Caulking is done on the edges of the plates as well as on, the edges of the rivet heads. But fullering is done on the, edges of the plate only. To facilitate caulking and fullering, on the plates, the edges of the plates are bevelled about 800, to 850., The strength of riveted joints: A riveted joint is only as, strong as its weakest part and it must be borne in mind that, it may fail in one of the following four ways., , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence, , 207
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-, , Shearing of the rivet, , -, , Crushing of the metal, , -, , Spliting of the metal, , -, , Rupture or tearing of the plate, , These four undesirable effects are illustrated in the table, below., Table, Riveted joints, , 208, , Effects, , Causes, , Prevention, , Shearing of, the rivet, , Diameter of the rivet too smal, compared with the thickness, of the plate. The diameter of, the rivet must be greater than, the thickness of the plate, in, which it is to be riveted. Strength, of trivet material is less when, compared to the materials of, the plates., , Select the correct diameter, rivet to suit thickness of, the plate. Select a suitable, material visit., , Crussing of the, rivet, , Diameter of the rivet too large, compared with the thickness, of the plate. The rivets when, driven tend to bulge and cursh, the metal in front of them., , Select the correct diameter, rivet for the thickness of the, metal plate., , Splitting of the, metal, , Rivet holes punched or drilled, too near the edge of the plate., Metal is likely to fail by splitting, in front of the rivets., , Drill or punch the rivet at, the correct distance from, the edge and use the, correct lap allowance for, the diameter of the rivet., , Tearing of the, plate, , Plates weakened by rivet, holes being too close together., Plates tend to rupture along, the centre line of the rivets, , Punch or drill rivet holes, at the correct spacing or, or pitch. In addition remove, all burrs from the holes, before final assembly., , P&M : Fitter - Related Theory for Exercise 1.3.52-55, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Welding, , Related Theory for Exercise 1.4.56, , Safety, Objectives: At the end of this lesson you shall be able to, • state the importance of safety in welding shop, • list the general safety precautions to be observed in welding shop., Safety, Welding can be dangerous and unhealthy if the proper, precautions are not taken. However, using new technology, and proper protection greatly reduces risks of injury and, death associated with welding. Since many common, welding procedures involve an open electric arc or flame,, the risk of burns and fire is significant, that is why it is, classified as a hot work process., To prevent injury, welders wear personal protective, equipment in the form of heavy leather gloves and protective, long-sleeve jackets to avoid exposure to extreme heat and, flames. Additionally, the brightness of the weld area leads, to a condition called arc eye or flash burns in which, ultraviolet light causes inflammation of the cornea and can, burn the retinas of the eyes. Goggles and welding helmets, with dark UV-filtering face plates are worn to prevent this, exposure., Since the 2000s, some helmets have included a face plate, which instantly darkens upon exposure to the intense UV, light. To protect bystanders, the welding area is often, surrounded with translucent welding curtains. These, curtains, made of a polyvinyl chloride plastic film, shield, people outside the welding area from the UV light of the, electric arc, but can not replace the filter glass used in, helmets., Welders are often exposed to dangerous gases and, particulate matter. Processes like flux-cored arc welding, and shielded metal arc welding produce smoke containing, particles of various types of oxides. The size of the, particles in question tends to influence the toxicity of the, fumes, with smaller particles presenting a greater danger., This is because smaller particles have the ability to cross, the blood brain barrier. Fumes and gases, such as carbondi-oxide, ozone, and fumes containing heavy metals, can, be dangerous to welders lacking proper ventilation and, training. Exposure to manganese welding fumes, for, example, even at low levels (<0.2 mg/m3) may lead to, neurological problems or to damage to the lungs, liver,, kidneys, or central nervous system. Nano particles can, become trapped in the alveolar macrophages of the lungs, , and induce pulmonary fibrosis. The use of compressed, gases and flames in many welding processes possess, an explosion and fire risk. Some common precautions, include limiting the amount of oxygen in the air, and, keeping combustible materials away from the workplace., General safety, •, , To prevent injury to personel, extreme caution should, be exercised when using any types of welding, equipment. Injury can result from fire, explosions,, electric shock, or harmful agents. Both the general, and specific safety precautions listed below must be, strictly observed by workers who weld or cut metals., , •, , Do not permit unauthorized persons to use welding or, cutting equipment., , •, , Do not weld in a building with wooden floors, unless, the floors are protected from hot metal by means of fire, resistant fabric, sand, or other fireproof material. Be, sure that hot sparks or hot metal will not fall on the, operator or on any welding equipment components., , •, , Remove all flammable material, such as cotton, oil,, gasoline, etc., from the vicinity of welding., , •, , Before welding or cutting, warm those in close proximity, who are not protected to wear proper clothing or, goggles., , •, , Remove any assembled parts from the component, being welded that may become warped or otherwise, damaged by the welding process., , •, , Do not leave hot rejected electrode stubs, steel scrap,, or tools on the floor or around the welding equipment., Accidents and/or fires may occur., , •, , Keep a suitable fire extinguisher nearby at all times., Ensure the fire extinguisher is in operable condition., , •, , Mark all hot metal after welding operations are, completed. Soapstone is commonly used for this, purpose., , 209, , Copyright Free Under CC BY Licence
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Safety precautions in handling gas welding plant, Objectives : At the end of this lesson you shall be able to, • state the general safety precautions in oxy-acetylene plants., • state the safety rules for handling gas cylinders, • state the safety practices for handling gas regulators and hose-pipes., • state the safety precautions related to blowpipe operations., To be accident-free, one must know the safety rules first, and then practise them as well. As we know can 'accident, starts when safety ends'., Ignorance of rules is no excuse!, , Even a small leakage can cause serious accidents., Always keep fire-fighting equipment handy and in working, order to put out fires. (Fig 3), Keep the work area free from any form of fire., , In gas welding, the welder must follow the safety precautions in handling gas welding plants and flame-setting to, keep himself and others safe., Safety precautions are always based on good common, sense., The following precautions are to be observed, to keep a, gas welder accident-free., General safety, Do not use lubricants (oil or grease) in any part or, assembly of a gas welding plant. It may cause explosion., Keep all flammable material away from the welding area., Always wear goggles with filter lens during gas welding., (Fig 1), , Safety precautions before gas welding, Safety for cylinders., Do not roll gas cylinders or use them as rollers., Use a trolley to carry the cylinders., Close the cylinder valves when not in use or empty., Keep full and empty cylinders separately., Always open the cylinder valves slowly, not more than, one and a half turn., Use the correct cylinder keys to open the cylinders., , Always wear fire resistant clothes, asbestos gloves and, apron., Never wear nylon, greasy and torn clothes, while welding., , Do not remove the cylinder keys from the cylinders while, welding. It will help to close the cylinders QUICKLY in the, case of a back-fire or flash-back., Always use the cylinders in an upright position for easy, handling and safety., Always crack the cylinder valves to clean the valve sockets, before attaching regulators. (Fig 4), , Whenever a leakage is noticed rectify it immediately to, avoid fire hazards. (Fig 2), , 210, , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence
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Safety for rubber hose pipes (Fig 5), , One right hand threaded connection for oxygen and left, hand threaded connection for acetylene., Safety for blowpipes, When a blowpipe is not in use put out the flame and place, the blowpipe in a safe place., When flame snaps out and backfires, quickly shut both, the blowpipe valves (oxygen first) and dip in water., While igniting the flame, point the blowpipe nozzle in a, safe direction. (Fig 6), , Inspect the rubber hose pipes periodically and replace the, damaged ones., Do not use odd bits of hose pipes / tubes., Do not replace the hose pipes for acetylene with the ones, used for oxygen., Always use a black hose pipes for oxygen and, maroon hosepipes for acetylene., Safety for regulators, Prevent hammer blows to the gas cylinders and ensure, that water, dust and oil do not settle on the cylinders., , While extinguishing the flame, shut off the acetylene valve, first and then the oxygen valve to avoid a backfire., , Safety precautions before, during, after arc welding, Objective : At the end of this lesson you shall be able to, • state the precautions necessary in arc-welding., Safety precautions, -, , Never stand on a damp or wet place while arc-welding., , -, , Always wear all the safety apparels (gloves, apron,, sleeves, shoes). (Fig 1), , -, , Use welding and a chipping screen during welding, and chipping respectively, for the protection of the eyes, and the face., , -, , Switch off the machine when not in use., , -, , Keep the clothes free from oil and grease., , -, , Use tongs while handling hot metals., , -, , Do not carry matches or petrol lighters in your pocket, during arc-welding., , -, , Protect the outsiders from radiation and reflection of, rays, by using portable screens or welding booths., (Fig 2), , -, , Keep the welding area free from moisture and flammable material., , -, , Do not try to rectify electrical faults yourself; call an, electrician., P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence, , 211
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-, , Do not throw the electrode stubs on the floor. Put them, in a container. (Fig 3), , -, , Use exhaust fans to remove the arc-welding smoke, and fumes. (Fig 4), , -, , Safety precautions after gas and electric welding after, working gas welding and gas cutting bleed the lines to, take pressure off regulators, neatly coil the hoses and, replace equipment., , -, , Store hoses, torches, blow pipes regulators safety in, proper place., , -, , Welding machines will be disconnected from the power, source., , -, , Store away the gas cylinders from in flammable and, combustible materials., , -, , Disconnect the welding cables from welding equipment., , -, , After electric welding operations are completed the, welder will mark the hot metal or provide some other, means of warning other workers., , -, , Neatly coil the cable and kept in place safety., , -, , Place and store electrode holder and other hand tools, safely., , _______, , 212, , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence
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Safety equipments and their uses in welding, Objectives : At the end of this lesson you shall be able to, • Name the safety apparels and accessories used in arc welding, • Select the safety apparels and accessories to protect from burns and injuries, • learn how to protect yourself and others from the effect of harmful arc rays and toxic fumes, • select the shielding glass for eye and face protection., Non-fusion welding, This is a method of welding in which similar or dissimilar, metals are joined together without melting the edges of, the base metal by using a low melting point filler rod but, without the application of pressure., Example: Soldering, Brazing and Bronze welding., During arc welding the welder is exposed to hazards such, injury due to harmful rays (ultra violet and infra red rays)of, the arc, burns due to excessive heat from the arc and, contact with hot jobs, electric shock, toxic fumes, flying, hot spatters and slag particles and objects falling on the, feet., The following safety apparels and accessories are used, to protect the welder and other persons working near the, welding area from the above mentioned hazards., 1 Safety apparels, a, , Leather apron, , b, , Leather gloves, , c, , Leather cape with sleeves, , d, , Industrial safety shoes, , 2 a, , Hand screen, , b, , Adjustable helmet, , C, , Portable fire proof canvas screens, , 3 Chipping/grinding goggles, 4 Respirator and exhaust ducting, The leather apron, glooves, cape with sleeves and leg, gaurd Fig 3,4,5 and 6 are used to protect the body, hands,, arms, neck and chest of the welder from the heat radiation, and hot spatters from the arc and also from the hot slag, particles flying from the weld joint during chipping off the, solidified slag., , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence, , 213
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All the above safety apparels should not be loose while, wearing them and suitable size has to be selected by the, welder., The industrial safety boot (Fig7)is used to avoid slipping., injury to the toes and ankle of the foot. It also protects the, welder from the electric shock as the sole of the shoe is, specially made of shock resistant material., , Clear glasses are fitted on each side of the coloured glass, to protect it from weld spatters. (Fig.10), , The helmet screen provides better protection and allows, the welder to use his both hands freely., Coloured (filter) glasses are made in various shades, depending on the welding current ranges used. (Table 1), Table 1, Recommendations of filter glasses for maual metal, arc welding, Shade No of, coloured glass, Welding hand screens and helmet: These are used to, protect the eyes and face of a welder from arc radiation, and sparks during arc welding., A hand screen is designed to hold in hand (Fig.8), , Range of welding current, current in amperes, , 8-9, , Up to 100, , 10-11, , 100 to 300, , 12-14, , Above 300, , Portable fire proof canvas screens. Fig.11 are used to, protect the persons who work near the welding area from, arc flashes, Plain goggles are used to protect the eyes while chipping, the slag or grinding the job. Fig12, , A helmet screen is designed to wear on the head.(Fig.9), , 214, , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence
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It is designed for comfortable fit, proper ventilation and full, protection from all sides., Sometimes toxic fumes and heavy smoke may be liberated, (given out) from the weld while welding non-ferrous alloys, like brass etc. Use a respirator and use exhaust ducts, and fans near the weld area to avoid inhaling the toxic, fumes and smoke. Fig13., Inhaling toxic fumes will make the welder to become, unconcious and fall on the hot welded job/ on the floor., This causes burns or injury., , It is made of Bakelite frame fitted with clear glasses and, an elastic band to hold it securely on the operator’s head., , _______, , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence, , 215
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Gas welding equipment and accessories, Objectives : At the end of this lesson you shall be able to, • brief the process of gas welding, • list the equipment used in gas welding, • state the functions of each equipment used in gas welding., Oxy-acetylene welding, popularly known as gas welding, is simple, cheap and easy to operate. The heat input can, be closely controlled to weld even thin, tiny components., In oxy-acetylene welding process, the metal is heated by, an intense flame (3300ºC) produced by burning proper, quantity of oxygen and acetylene at the tip of welding, torch. The flame is directed towards the weld location to, melt the metal to be joined and are fused together thus, producing weld., Gas welding equipment, The principle function of the oxy-acetylene welding, equipment is to supply the oxy-acetylene gas mixture in, the correct ratio to the welding tip at the correct rate of, flow and velocity. (Fig 1), , •, , Acetylene gas hose (Maroon), , •, , Welding torch or blow pipe with a set of nozzles and, gas lighter., , •, , Tralleys for transportation of oxygen and acetylene, cylinder., , •, , A set of keys and spanners, , •, , Filler rod and fluxes, , •, , Protective clothing for welder (Leather apron, gloves,, goggles, etc), , Oxygen gas cylinders: The oxygen gas required for gas, welding is stored in bottle-shaped cylinders. These, cylinders are painted in black colour. (Fig 2) Oxygen, cylinders can store gas to a capacity of 7m3 with the, pressure ranging between 120 to 150 kg/cm2. Oxygen, gas cylinder valves are right hand threaded., , The basic equipments used to carry out gas welding are, Dissolved acetylene cylinders: The acetylene gas used, in gas welding is stored in steel bottles (cylinders) painted, in maroon colour. The normal storing capacity of storing, acetylene in dissolved state is 6m3 with the pressure, ranging between 15-16 kg/cm2., , •, , Oxygen gas cylinder, , •, , Acetylene gas cylinder, , •, , Oxygen pressure regular, , •, , Oxygen gas hose (black/green), , 216, , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence
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Oxygen pressure regulator: This is used to reduce the, oxygen cylinder gas pressure according to the required, working pressure and to control the flow of oxygen at a, constant rate to the blowpipe. The threaded connections, are right hand threaded. (Fig 3), , Acetylene regulator: As with the case of oxygen, regulator this also is used to reduce the cylinder gas, pressure to the required working pressure and to control, the flow of acetylene gas at a constant rate to the blowpipe., The threaded connections are left handed. For quickly, identifying the acetylene regulator, a groove is cut at the, corners of the nut.(Fig 4), , Rubber hoses are connected to regulators with the help of, unions. These unions are right hand threaded for oxygen, and left hand threaded for acetylene. Acetylene hose unions, have a groove cut on the corners. (Fig 6), , At the blowpipe end of the rubber hoses hose-protectors, are fitted. The hose protectors are in the shape of a, connecting union and have a non-return disc fitted inside, to protect from flashback and backfire during welding., (Fig 7), , Rubber hose-pipes and connections: These are used, to carry gas from the regulator to the blowpipe. These are, made of strong canvas rubber having good flexibility. Hosepipes which carry oxygen are black in colour and the, acetylene hoses are of maroon colour. (Fig 5), Blowpipe and nozzle: Blowpipes are used to control, and mix the oxygen and acetylene gases to the required, proportion. (Fig 8), , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence, , 217
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The size of the nozzle varies according to the thickness of, the plates to be welded. (Table 1), TABLE 1, Plate thickness, (mm), , Nozzle size, (Number), , 0.8, 1.2, 1.6, 2.4, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0, 12.0, 19.0, 25.0, Over 25.0, , A set of interchangeable nozzles/tips of different sizes is, available to produce smaller or bigger flames. (Fig 9), , 1, 2, 3, 5, 7, 10, 13, 18, 25, 35, 45, 55, 70, 90, , _______, , Arc welding machines and accessories, Objectives : At the end of this lesson you shall be able to, • state the function of arc-welding machines, • name the different types of arc-welding machines., In the arc-welding process, the source of heat is electricity, (high ampere low voltage). This heat is supplied by the, arc-welding machine which is the power source., Function (Fig 1), , Types (Fig 2), Basically the power sources are, , The equipment is used to, − provide A.C. or D.C. supply for arc welding, − change the high voltage of main supply (A.C.) to low, voltage, heavy current (A.C. or D.C.) suitable for arc, welding, , 218, , − control and adjust the required supply of current during, arc welding, , − alternating current (A.C.) welding machine, − direct current (D.C.) welding machine., , P&M : Fitter - Related Theory for Exercise 1.4.56, , Copyright Free Under CC BY Licence
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A.C.Machines, − Transformer sets, A.C. means Alternating Current. It changes or reverses, its direction of flow 50-60 cycles per second. (Fig 3), , D.C. means Direct Current. It flows steadily and constantly, in one direction. (Fig 4), , These may be further classified as, − D.C.Machines, − motor generator set, − engine generator set, − rectifier sets., , A.C. welding transformer and welding generator, Objectives : At the end of this lesson you shall be able to, • state the features of A.C. welding transformers, • state the advantages and disadvantages of A.C. welding machines., A.C. welding transformer, An A.C.welding transformer is a type of A.C. welding, machine which converts the A.C. main supply into an A.C., welding supply. (Figs 1 and 2), The A.C. main supply has high voltage - low ampere., The A.C. welding supply has high ampere - low voltage., It is a STEP-DOWN transformer which reduces the main, supply voltage (220 or 440 volts) to the welding supply, open circuit voltage (O.C.V.), between 40 and 100 volts., It increases the main supply low current to the required, output welding current in a hundred or thousand amperes., The A.C. welding machine cannot be operated without the, A.C. main supply., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 219
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Advantages, -, , Less initial cost, , -, , Less maintenance cost, , -, , Freedom from arc blow., , Magnetic effect which disturbs the arc is called the arc, blow., Disadvantages, -, , Not suitable for the welding of non-ferrous metals, light, coated and special electrodes., , -, , The A.C. cannot be used without special safety, precautions., , D.C. Arc-welding machines, Objectives : At the end of this lesson you shall be able to, • state the features of a D.C. welding machine, • state its advantages and disadvantages., Motor generator set (Fig 1), , Engine generator set (Fig 2), , It is used to generate D.C. for arc-welding., The generator is driven by an A.C. or D.C. motor., Main supply is a must to run the machine., , Equipment is similar to the motor generator set except, that the generator is driven by a pertrol or diesel engine., Its running and maintenance charges are higher., It can be used anywhere in field work, away from electric, lines., Rectifier set (Fig 3), It is used to convert A.C. into D.C. welding supply., , 220, , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence
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Basically it is an A.C. welding transformer. The output of, the transformer is connected with a rectifier to change the, A.C. into D.C., It may be designed to supply both A.C. and D.C. currents, for welding (called A.C.-D.C. rectifier set)., Advantages, Suitable for welding all ferrous and non-ferrous metals using, all types of electrodes, -, , Better heat distribution in the electrode and job due to, polarity in the welding current supplies constant main, load and accurate current setting., , It ensures safe working., Disadvantages, -, , Initial cost is higher, , -, , Maintenance cost is more, , -, , Arc-blow trouble faced at certain times., , Polarity in arc welding, Objectives : At the end of this lesson you shall be able to, • state what is polarity in arc welding, • state the types of polarity., Polarity in D.C. power source, , Straight polarity (Fig 2), , The polarity of a machine refers to the direction of the, current flow., , When the electrode cable is connected to the negative, terminal as it is called negative polarity or straight polarity., , The polarity can be obtained only in D.C., , Remember, , Polarity may be straight or reverse., , A.C. has no polarity, , Reverse polarity (Fig 1), , The total heat produced in D.C. arc consists of 2/3 heat, from the POSITIVE Terminal (66%) and 1/3 heat from the, NEGATIVE Terminal (33%)., , When the electrode cable is connected to the positive, terminal, it is called positive polarity or reverse polarity., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 221
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Arc length and its effects, Objectives : At the end of this lesson you shall be able to, • state what is arc length, • differentiate normal arc, length arc and short arc, • explain the effects of different arc lengths., Arc length (Fig 1), It is the straight distance between the electrode tip and, the job surface when an arc is formed., There are three types of arc length., -, , Normal, , -, , Long, , -, , Short, , Short arc length (Fig 4), If the distance between the tip of the electrode and the, base metal is less than the dia. of the core wire, it is, called a ‘short arc’., , Normal arc length (Fig 2), The correct arc length or normal arc length is approximately, equal to the diameter of the core wire of the electrode., , Effects of arc length, -, , A long arc makes a humming sound, , -, , The arc is unstable, , -, , Causes oxidation of the weld metal., , -, , Fusion and penetration are poor., , -, , Poor control of the molten metal., , -, , Creates more spatters resulting in wastage of the, electrode metal., , Long arc length (Fig 3), , Short arc, , If the distance between the tip of the electrode and the, base metal is more than the diameter of the core wire, it is, called ‘long arc’., , -, , It makes a popping sound., , -, , The electrode to melt slowly and try to freeze the job., , -, , Higher metal deposition with narrow width bead., , -, , Less spatters., , -, , Fusion and penetration is less., , 222, , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence
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Normal arc, , -, , Correct fusion and penetration., , -, , A stable arc produces a steady sharp crackling sound, , -, , The size of metal deposition is correct., , -, , Electrode burns evenly., , -, , Less spatters., , Faults in arc welding, Objective : At the end of this lesson you shall be able to, • name the visible and invisible defects of weldments., Weld defects, , Visible faults, , An imperfection in the weld, by which resulting in loss of, strength, is known as weld fault or defect. (Fig 1), , These are visible to the naked eye on the weld surface., (Fig 2), , Invisible, These faults are inside the weld metal and cannot be seen, by the naked eye. (Fig 3), Types, Weld faults are classified as:, -, , Visible faults, and, , -, , Invisible faults., , Defective welds can result in grave damage to, Men and materials., , _______, , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 223
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Production & Manufacturing, Fitter - Welding, , Related Theory for Exercise 1.4.57 & 58, , Welding hand tools, Objectives: At the end of this lesson you shall be able to, • name the hand tools used by a welder, • state their uses, • state the care and maintenance to keep the hand tools in good working condition., The following are the details of different hand tools used, by a welder., Double ended spanner: A double ended spanner is, shown in Fig.1 and 1a. It is made of forged chrome vanadium, steel. It is used to loosen or tighten nuts, bolts with, hexagonal or square heads. The size of the spanner is, marked on it as shown in Fig.1. In welding practice the, spanners are used to fix the regulator onto the gas cylinder, valves, hose connector and protector to the regulator and, blow pipe, fix the cable lugs to the arc welding machine, output terminals, etc., , Tip cleaner: A special tip cleaner is supplied with the, torch container. For each tip there is a kind of drill and a, smooth file Fig.3., , Do not use the spanner as a hammer; use the correct, size spanner to avoid damage to the nut/bolt head., Cylinder key: A cylinder key is shown in Fig.2. It is used, to open or close the gas cylinder valve socket to permit or, stop the gas flow from the cylinder to the gas regulator., , Before cleaning the tip, select the correct drill and move, it, without turning, up and down through the hole in the tip, Fig.4., , Always use correct size key to avoid damage to the square, rod used to operate the valve. The key must always be left, on the valve socket itself so that the gas flow can be, stopped immediately in case of flash back/back fire., Nozzle or tip cleaner, Cleaning the tip: All welding torch tips are made of, copper. They can be damaged by the slightest rough, handling-dropping, tapping or chopping with the tip on the, work may damage the tip beyond repair., 224, , Copyright Free Under CC BY Licence
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The smooth file is then used to clean the surface of the tip, Fig.5. While cleaning, leave the oxygen valve partly open, to blow out the dust., , Carbon steel wire brush: A carbon steel wire brush is, shown in Fig.9. It is used for, , – Cleaning the work surface from rust, oxide and other, dirt etc. prior to welding., Spark lighter: The spark lighter, as illustrated in Fig.6 &, 7 is used for igniting the torch. While welding, form the, habit of always employing a spark lighter to light a torch., Never use matches. The use of matches for this purpose, is very dangerous because the puff of the flame produced, by the ignition of the acetylene flowing from the tip is likely, to burn your hand., , – Cleaning the interbead weld deposits after chipping off, the slag., – General cleaning of the weldment., A stainless steel wire brush is used for cleaning a non, ferrous and stainless steel welded joint., It is made of bunch of steel wires fitted in three to five rows, on a wooden piece with handle. The wires are hardened, and tempered for long life and to ensure good cleaning, action., Tongs: Fig.10 and Fig.11 shows a pair of tongs used to, hold hot work pieces and to hold the job in position., , Welding hand screen (Fig 12), Chipping hammer: The chipping hammer (Fig.8) is used, to remove the slag which covers the deposited weld bead., It is made of medium carbon steel with a mild steel handle., It is provided with a chisel edge on one end and a point on, the other end for chipping off slag in any position., , A welding hand screen is used to shield and protect the, face and the eyes from the arc radiation., It is fitted with a filter lens, and plain glass to protect the, lens., , Care should be taken to maintain the sharp chisel edge, and the point for effective chipping of slag., P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 225
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Welding helmet screen (Fig 13), It is used as a hand screen but it can be worn on the head, of the welder to enable him to use both his hands ., , The cable is insulated with a good quality flexible rubber,, and copper core wires, to carry the high current from the, welding machines., Earth clamp with cable (Fig 17), , Chipping goggles (Fig 14), Chipping goggles are used to protect the eyes while, chipping the slag., They are fitted with a plain glass to see the area to be, cleaned., , An earth clamp is used to connect the return lead firmly to, the job or to the welding table., Welding table, The welding table is used to keep the jobs and assemble, the pieces during welding. The top of the table is made of, metal., Apron (Fig 18), , Tong (Fig 15), Tongs are used to handle the hot metal-welding job while, cleaning., They are also used to hold the metal for hammering., An apron is used to protect the body., It should be made of leather and worn., It must be worn for protection from the radiation of the, heat rays and hot spatters., Hand gloves (Fig 19), , Electrode holder with cable (Fig 16), , Hand gloves are used to protect the hands from electrical, shock, arc radiation, heat, and hot spatters., The gloves are also made of leather., An electrode holder is used to hold and manipulate the, electrode., P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, 226, , Copyright Free Under CC BY Licence
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Arc welding accessories, Objectives : At the end of this lesson you shall be able to, • name the arc welding accessories, • explain the function of each accessory., Arc welding accessories: Some very important items, used, by a welder with an arc welding machine during the welding operation, are called arc welding accessories., , Welding cables/leads: These are used to carry the welding current from the welding machine to the work and, back., , Electrode-holder(Fig 1): It is a clamping device used to, grip and manipulate the electrod eduring arc welding. It is, made of copper/copper alloy for better electrical conductivity., , The lead from the welding machine to the electrode-holder, is called electrode cable., The lead from the work or job through the earth clamp to, the welding machine is called earth(ground)cable., Cables are made of super flexible rubber insulation,having, fine copper wires and woven fabric reinforcing layers., (Fig 4), , Partially or fully insulated holders are made in various, sizes i.e 200-300-500 amps, The electrode-holder is connected to the welding machine, by a welding cable., Earth clamp(Fig 2): It is used to connect the earth cable, firmly to the job or welding table. It is also made of copper/copper alloys., , Welding cables are made in various sizes (cross-sections) i.e.300, 400,600 amps etc., The same size welding cables must be used, for the electrode and the job., The cable connection must be made with suitable cable attachments (lugs) (Fig 5)., , Screw or spring-loaded earth clamps are made in various, sizes i.e. 200-300-500 amps. (Fig 3), , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 227
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Loose joints or bad contacts cause overheating of the, cables., The length of the cable has considerable effect on the, size to be used. (See Table 1)., Voltage drop app. 4 volts with all connections clean and, tight., , Table 1, Recommendations of copper cable for arc weldCable, dia. (mm), , Length of cable in metres, Current capacity in am0 - 15, , 15 - 30, , 24.0, , 600, , 600, , 400, , 21.0, , 500, , 400, , 300, , 19.0, , 400, , 350, , 300, , 18.0, , 300, , 300, , 200, , 16.5, , 250, , 200, , 175, , 15.0, , 200, , 195, , 150, , 14.5, , 150, , 150, , 100, , 13.5, , 125, , 100, , 75, , Hammer, Objectives : At the end of this lesson you shall be able to, • state the uses of an engineer’s hammer, • name the parts of an engineer’s hammer and state their functions, • name the types of engineer’s hammers, • specify the engineer’s hammer., An engineer’s hammer is a hand tool used for striking, purposes while, , - Punching (Fig.1), - Bending, - Straightening, - Chipping, - Peening(Fig.2), - forging, - riveting, , 228, , 30 - 75, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Major parts of a hammer: The major parts of a hammer, are a head and a handle., The head is made of drop-forged carbon steel, while the, wooden handle must be capable of absorbing shock., The parts of a hammer-head are the face, pein, cheek,, eye hole(Fig 3), , Face: The face is the striking portion, Slight convexity is, given to it to avoid digging of the edge into the job., Peen or Pein: The pein is the other end of the head. It is, used for shaping and forming work like riveting. Peening, and bending. The pein is of different shapes(Fig.4) like the, , Specification: An engineer’s hammer is specified by their, wegiht and the shape of the pein. Their weight varies from, 125g to 1500 g., , Ball pein, , The weight of an engineer’s hammer, used by a welder is, 1000 g and for making purposes, is 500g., , Cross pein, , The ball pein hammers are used for general work in a, workshop., , straight pein, , Before using a hammer, -, , Make sure the handle is properly fitted., , -, , Select a hammer with the correct weight suitable for the job., , -, , Check the head and handle for any cracks., , -, , Ensure the face of the hammer is free from, oil or grease., , -, , Always the handle is to be held at its extreme, end while hammering., , The face and the pein are hardened., A welder uses the ball pein hammer for punching,chiseling,, peening, removing bends and for straightening of sheets., Cheek: The cheek is the middle portion of the hammer, head.The weight of the hammer is stamped here., This portion of the hammer-head is left soft., Eye hole: An eye hole is meant for fixing the handle. It is, shaped to fit the handle rigidly. The wedges fix the handle, in the eye hole. (See Figs 5 and 6), , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 229
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Types and uses of welding processes, Objectives : At the end of this lesson you shall be able to, • state the classify the electric welding processes, • state the classify the gas welding processes, • name and classify the other welding processes, • state the applications of various welding processes., According to the sources of heat, welding processes can, be broadly classified as:, -, , Electric welding processes(heat source is electricity), , -, , Gas welding processes (heat source is gas flame), , -, , Other welding processes (heat source is neither electricity nor gas flame), , Electric welding processes can be classified as:-, , Electric arc welding, , -, , Electric resistance welding, , -, , Laser welding, , -, , Electron beam welding, , -, , Induction welding, , Electric arc welding can be further classified as:, -, , Shielded Metal Arc Welding/Manual Metal Arc Welding, , -, , Ultrasonic welding, , -, , Explosive welding, , -, , Cold pressure welding, , -, , Plastic welding, , Code, , Welding process, , AAW, , Air Acetylene, , AHW, , Atomic Hydrogen, , BMAW, , Bare Metal Arc, , CAW, , Carbon Arc, , EBW, , Electron Beam, , ESW, , Electro Gas, , ESW, , Electroslag, , FCAW, , Flux cored Arc, , FW, , Flash, , -, , Carbon arc welding, , FLOW, , FLOW, , -, , Atomic hydrogen arc welding, , GCAW, , Gas Carbon Arc, , -, , Gas Tungsten Arc Welding / TIG Welding, , GMAW, , Gas Metal Arc, , -, , Gas Metal Arc Welding / MIG/MAG Welding, , GTAW, , Gas Tungsten Arc, , -, , Flux cored arc welding, , IW, , Induction, , -, , Submerged arc welding, , LBW, , Laser Beam, , -, , Electro-slag welding, , OAW, , Oxy-Acetylene, , -, , Plasma arc welding., , OHW, , Oxy-Hydrogen, , Electric resistance welding can be further classified as:, , PAW, , Plasma Arc, , -, , Spot welding, , PGW, , Pressure Gas, , -, , Seam welding, , RPW, , Resistance Projection, , -, , Butt welding, , RSEW, , Resistance Seam, , -, , Blash butt welding, , SAW, , Submerged Arc, , Projection welding, , SMAW, , Shielded Metal Arc, , Gas welding processes can be classified as:, , SCAW, , Shielded Carbon Arc, , -, , Oxy-acetylene gas welding, , SW, , Stud Arc, , -, , Oxy-hydrogen gas welding, , TW, , Thermit, , The other welding processes are:, , UW, , Ulrosonic, , -, , Thermit welding, , -, , Forge welding, , -, , Friction welding, , 230, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Applications of various welding processes, Forge welding : It is used in olden days for joining metals as a lap and butt joint., Shielded Metal arc welding is used for welding all ferrous and non-ferrous metals using consumable stick electrodes., Carbon arc welding is used for welding all ferrous and, non-ferrous metals using carbon electrodes and separate, filler metal. But this is a slow welding process and so not, used now-a-days., Submerged arc welding is used for welding ferrous metals, thicker plates and for more production., Co welding (Gas Metal Arc Welding) is used for welding ferrous metals using continuously fed filler wire and, shielding the weld metal and the arc by carbon-di-oxide, gas., TIG welding (Gas Tungsten Arc Welding) is used for, welding ferrous metals, stainless steel, aluminium and, thin sheet metal welding., Atomic hydrogen welding is used for welding all ferrous and non-ferrous metals and the arc has a higher temperature than other arc welding processes., , Plasma arc welding: The arc has a very deep pentrating, ability into the metals welded and also the fusion is taking, place in a very narrow zone of the joint., Spot welding is used for welding thin sheet metal as a, lap joint in small spots by using the resistance property of, the metals being welded., Seam welding is used for welding thin sheets similar to, spot welding. But the adjacent weld spots will be overlapping each other to get a continuous weld seam., Projection welding is used to weld two plates one over, the other on their surfaces instead of the edges by making projection on one plate and pressing it over the other, flat surface. Each projection acts as a spot weld during, welding., Butt welding is used to join the ends of two heavy section rods/blocks together to lengthen it using the resistance property of the rods under contact., Flash butt welding is used to join heavy sections of rods/, blocks similar to butt welding except that arc flashes are, produced at the joining ends to melt them before applying, heavy pressure to join them., , Electroslag welding is used for welding very thick steel, plates in one pass using the resistance property of the, flux material., , Principle and method of operating of arc welding, Objectives : At the end of this lesson you shall be able to, • state the methods of operating the ARC welding., When high current passes through an air gap from one, conductor to another, it produces very intense and concentrated heat in the form of a spark. The temperature of, this spark(or arc) is app. 3600°C, which can melt and fuse, the metal very quickly to produce a homogeneous weld, (Fig 1), , Carbon arc welding (Fig 3): Here the arc is formed between a carbon electrode (non-consumable)and the welding job., A separate filler rod is used since the carbon electrode is, a non-metal and will not melt., Shielded Metal Arc welding (Fig 2): This is an arc welding process in which the welding heat is obtained from an, arc, formed between a metallic (consumable) electrode, and welding job., The metal electrode itself melts and acts as a filler metal., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 231
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Tungsten inert gas arc welding(TIG) (Fig 5): In this case, the arc is formed between the tungsten electrodes (nonconsumable) and the welding job in an atmosphere of an, inert gas (argon or helium), A separate filler rod is used to add the filler metal, This process is also called gas tungsten arc welding, (GTAW)process., , Atomic hydrogen arc welding (Fig4): In this process, the arc is formed between two tungsten electrodes in an, atmosphere of hydrogen gas., The welding job remains out of the welding circuit., A separate filler rod is used to add the filler metal., Gas metal arc welding (GMAW) or Metal inert gas, arc welding (MIG) (Fig 6): In this process the arc is formed, between a continous, automatically fed, metallic consumable electrode and welding job in an atmosphere of inert, gas, and hence this is called metal inert gas arc welding, (MIG) process., When the inert gas is replaced by carbon dioxide then it, is called CO arc welding or metal active gas (MAG) arc, welding., The common name for this process is gas metal arc, welding(GMAW), Submerged arc welding (Fig7): Here the arc is formed, between a continous, automatically fed, metallic consumable electrode and the welding job under a heap of powdered/granulated flux., The arc is totally submerged in the flux (invisible), , 232, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Electro-slag welding (Fig 8): The arc is formed between, a continous, automatically fed, metallic consumable electrode and the welding job under a thick pool of molten flux, (slag)., , The process is similar to TIG welding., Plasma cutting is used to cut non-ferrous metals and alloys successfully and quickly., , This automatic process requires special equipment and, is used only in vertical position for the welding of heavy, thick plates., Plasma arc welding(Fig 9): In this process the arc is formed, between a tungsten electrode and the welding job in an, atmosphere of plasma-forming gas-nitrogen, hydrogen and, argon., A separate filler rod is used to add the filler metal in the, joint. if necessary. But normally no filler rod is used., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 233
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Material preparation method, Objectives : At the end of this lesson you shall be able to, • State the necessity of preparing the materials to be welded, • State different methods used to cut mild steel sheets and plates to the required size before welding, • Name different tools and equipments used to prepare the mild steel sheets and plates., Necessity of materials prepartion for welding: While, fabricating(producing or making)different components/parts, by welding, different sizes of plates, sheets, pipes, angles,, channels with different dimensions are joined together to, get the final objects. For example, a railway compartment,, an aeroplane, an oil or water pipe line, a gate, a window grill,, a stainless steel milk tank, etc. So these objects can be, made to the required dimensions only by cutting them from, the larger size sheets, plates, pipes etc. which are available, in standard sizes, thickness, diameters and lengths in the, market. Hence cutting and preparing the base metal to the, required dimensions from the original material available in, many store is necessary before welding them., Also the base metals before cutting them to size will have, impurities like dirt, oil, paint, water and surface oxides, due, to long storage., These impurities will affect the welding and will create, some defects in the welded joint. These defects will make, the joint weak and it is possible that the welded joint will, break, if the weld defects are present in the welded joints., So in order to get a strong welded joint, it is necessary to, clean the surfaces to be joined and remove the dirt, oil, paint, water, surface oxide etc. from the joining surfaces, before welding., , Different methods used to cut metals, 1 By chiselling the sheets, 2 By hacksawing, 3 By shearing using hand lever shear, 4 By using guillotine shear, 5 By gas cutting, For thin sheets the first 4 methods are used. For thick, materials method 2,4 and 5 are used., Tools and equipments used to cut metals, 1, , Cold chisel, , 2 Hacksaw blade with frame, 3 Hand lever shear, 4 Guillotine shear, 5 Oxy-acetylene cutting torch, The cut edges of the sheet or plate are to be filed to remove, burrs and to make the edges to be square(at 90°angle)with, each other. For ferrous metal plates,which are more than, 3mm thick, the edges can be prepared by grinding them on, a bench/pedestal grinding machine., , Welding description (fusion, non-fusion and pressure), Objectives : At the end of this lesson you shall be able to, • distinguish between fusion and non-fusion welding, • state the method of pressure welding., Welding is a method of joining metals permanently., The method used in ancient days was forge welding., Types of welding, Fusion welding (Fig 1), , A method of welding in which similar metals are joined, together by melting and fusing their joining edges with or, without the addition of filler metal but without the application, of any kind of pressure is known as fusion welding. The, joint made is permanent. The common heating sources, are arc welding and gas welding., Non fusion welding, A method of welding in which similar or dissimilar metals, are joined together without melting the edges is known as, non-fusion welding. A low melting point filler rod is fused, between the joints without the application of pressure., (Fig 2) The joint made is temporary., The heat source may be arc or gas welding as in fusion, welding., , 234, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Pressure welding is a method of welding in which similar, metals are joined together by heating them to a plastic or, molten state and are then joined by pressing or hammering, without the use of the filler metal., The joint made is permanent., Examples of non-fusion welding are silver soldering, brazing, etc., , The heat source may be a blacksmith forge (forge welding), or electric resistance (resistance welding)., , Pressure welding (Fig 3), , Welding processes, Objectives : At the end of this lesson you shall be able to, • list the different welding process, • describe the welding process of SMAW, GMAW & GTAW, • select the welding process depending up on the requirements., Welding Processes, •, , •, , The number of different welding processes has grown, in recent years. These processes differ greatly in the, manner in which heat and pressure (when used) are, applied, and in the type of equipment used. There are, currently over 50 different types of welding processes;, we’ll focus on 3 examples of electric arc welding, which, is the most common form of welding., The most popular processes are shielded metal arc, welding (SMAW), gas metal arc welding (GMAW) and, gas tungsten arc welding (GTAW)., , •, , All of these methods employ an electric power supply, to create an arc which melts the base metal(s) to form, a molten pool. The filler wire is then either added, automatically (GMAW) or manually (SMAW & GTAW), and the molten pool is allowed to cool., , •, , Finally, all of these methods use some type of flux or, gas to create an inert environment in which the molten, pool can solidify without oxidizing., , Shielded Metal Arc Welding (SMAW) (Fig 1), SMAW is a welding process that uses a flux covered metal, electrode to carry an electrical current. The current forms, an arc that jumps a gap from the end of the electrode to, the work. The electric arc creates enough heat to melt, both the electrode and the base materials. Molten metal, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 235
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from the electrode travels across the arc to the molten, pool of base metal where they mix together. As the arc, moves away, the mixture of molten metals solidifies and, becomes one piece. The molten pool of metal is, surrounded and protected by a fume cloud and a covering, of slag produced as the coating of the electrode burns or, vaporizes (Fig 2). Due to the appearance of the electrodes,, SMAW is commonly known as ‘stick’ welding., , SMAW is one of the oldest and most popular methods of, joining metal. Moderate quality welds can be made at low, speed with good uniformity. SMAW is used primarily, because of its low cost, flexibility, portability and versatility., Both the equipment and electrodes are low in cost and, very simple. SMAW is very flexible in terms of the material, thicknesses that can be welded (materials from 1.5mm, thick to several millimeter thick can be welded with the, same machine and different settings). It is a very portable, process because all that’s required is a portable power, supply (i.e. generator). Finally, it’s quite versatile because, it can weld many different types of metals, including cast, iron, steel, nickel & aluminum., , 236, , Some of the biggest drawbacks to SMAW are (1) that it, produces a lot of smoke & sparks, (2) there is a lot of, post-weld cleanup needed if the welded areas are to look, presentable, (3) it is a fairly slow welding process and (4), it requires a lot of operator skill to produce consistent, quality welds., Gas Metal Arc Welding (GMAW) (Fig.3), In the GMAW process, an arc is established between a, continuous wire electrode (which is always being, consumed) and the base metal. Under the correct, conditions, the wire is fed at a constant rate to the arc,, matching the rate at which the arc melts it. The filler metal, is the thin wire that’s fed automatically into the pool where, it melts. Since molten metal is sensitive to oxygen in the, air, good shielding with oxygen-free gases is required. This, shielding gas provides a stable, inert environment to protect, the weld pool as it solidifies. Consequently, GMAW is, commonly known as MIG (metal inert gas) welding. Since, fluxes are not used (like SMAW), the welds produced are, sound, free of contaminants, and as corrosion-resistant, as the parent metal. The filler material is usually the same, composition (or alloy) as the base metal. (Fig.4), GMAW is extremely fast and economical. This process, is easily used for welding on thin-gauge metal as well as, on heavy plate. It is most commonly performed on steel, (and its alloys), aluminum and magnesium, but can be, used with other metals as well. It also requires a lower, level of operator skill than the other two methods of electric, arc welding discussed in these notes. The high welding, rate and reduced post-weld cleanup are making GMAW, the fastest growing welding process., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Tungsten’s extremely high melting temperature and good, electrical conductivity make it the best choice for a nonconsumable electrode. The arc temperature is typically, around 11,000° F. Typical shielding gasses are Argon (Ar),, Helium (He), Nitrogen (N) or a mixture of the two. As with, GMAW, the filler material usually is the same composition, as the base metal., , Gas Tungsten Arc Welding (GTAW) (Fig. 5), In the GTAW process, an arc is established between a, tungsten electrode and the base metal. Under the correct, conditions, the electrode does not melt, although the work, does at the point where the arc contacts and produces a, weld pool. The filler metal is thin wire that’s fed manually, into the pool where it melts. Since tungsten is sensitive to, oxygen in the air, good shielding with oxygen-free gas is, required. The same inert gas provides a stable, inert, environment to protect the weld pool as it solidifies., Consequently, GTAW is commonly known as TIG (tungsten, inert gas) welding. Because fluxes are not used (like, SMAW), the welds produced are sound, free of, contaminants and slags, and as corrosion-resistant as, the parent metal., , GTAW is easily performed on a variety of materials, from, steel and its alloys to aluminum, magnesium, copper,, brass, nickel, titanium, etc. Virtually any metal that is, conductive lends itself to being welded using GTAW. Its, clean, high-quality welds often require little or no postweld finishing. This method produces the finest, strongest, welds out of all the welding processes. However, it’s also, one of the slower methods of arc welding., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 237
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Co2 welding equipment and process, Objectives: At the end of this lesson you shall be able to, • state the main difference between shielded metal arc welding and co2 welding, • state the principle of co2 welding., Introduction to Co2 welding: Fusion welding of metal, plates and sheets is the best method of joining metals, because in this process the welded joint will possess the, same properties and strength as the base metal., Without a perfectly shielded arc and molten puddle, the, atmospheric oxygen and nitrogen will get absorbed by the, molten metal. This will result in weak and porous welds., In shielded metal arc welding (SMAW) the arc and molten, metal are protected/shielded by the gases produced by, the burning of the flux coated on the electrode., The above mentioned shielding action can be done by, passing an inert gas such as argon, helium, carbon-dioxide through the welding torch/gun. The arc is produced, between the base metal and a bare wire consumable, electrode fed continously through the torch., Principle of GMA welding: In this welding process, an, arc is struck between a continuously fed consumable bare, wire electrode and the base metal. The heated base metal,, the molten filler metal and the arc are shielded by the flow, of inert/noninert gas passing through the welding torch/, gun. (Fig.1), If an inert gas is used to protect the arc produced by a, consumable metal electrode, this process is called Metal, Inert Gas Welding (MIG)., , Basic equipment for a typical GMAW semiautomatic, setup (Fig 2), •, , Welding Power Source - provides welding power., , •, , Wire Feeders - controls supply of wire to welding gun., , •, , Supply of Electrode Wire., , •, , Welding Gun - delivers electrode wire and shielding, gas to the weld puddle., , •, , Shielding Gas Cylinder - provides a supply of shielding, gas to the arc., , When carbon-dioxide is used for shielding purposes, it is, not fully inert and it partly becomes an active gas. So Co2, welding is also called as Metal Active Gas (MAG) welding., MIG/MAG welding is a name with respect to gas, used for shields purpose, On the other hand Gas Metal Arc Welding is the, common name., , 238, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 239
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Selection of the welding process, Objectives: At the end of this lesson you shall be able to, • list the factors considered for selecting welding process, • state the advantages and disadvantages of welding process., Selection of the welding process, , •, , Appearance of the finished product, , The selection of the joining process for a particular job, depends upon many factors. There is no one specific rule, governing the type of welding process to be selected for a, certain job. A few of the factors that must be considered, when choosing a welding process are, , •, , Size of the parts to be joined, , •, , Time available for work, , •, , Skill experience of workers, , •, , Cost of materials, , •, , Code or specification requirements, , •, , Availability of equipment, , •, , Respectiveness of the operation, , •, , Quality requirements(base metal penetration,, consistency, etc), , •, , Location of work, , •, , Materials to be joined, , When selecting one process over the others, it is often, useful to examine the principal of each type of welding, covered in this lesson., , Welding process, SMAW, , GMAW, , GTAW, , 240, , General guidelines for selecting one process over, another, , Advantages, Cheap, , Disadvantages, Major post-weld cleaning, , Portable (no gas required), , Relatively 'dirty' method of welding, (sparks/fumes), , Versatile (can weld various, metals & thicknesses), , Requires moderate skill, , Fastest of all 3 processes, , Requires shielding gas, , Versatile (can weld various, metals & thicknesses), , Minor post-weld cleaning, , Highest quality welds, , Requires shielding gas, , No post-weld cleaning, , Slowest of all 3 processes, , Versatile (can weld various, metals & thicknesses), , Requires high degree of operator skill, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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HP & LP welding equipments description, principle and method of operating, Objectives : At the end of this lesson you shall be able to, • Explain the low pressure and the high pressure systems of oxy-acetylene plants and systems, • distinguish between low pressure and high pressure blowpipes, • State the advantages and disadvantages of both systems., Oxy-acetylene plants: An oxy-acetylene plant can be, classified into:, high pressure plant, low pressure plant, A high pressure plant utilises acetylene under high pressure (15 kg/cm) (Fig1), , The terms low pressure and high pressure, systems used in oxy-acetylene welding refer, only to acetylene pressure, high or low., Types of blowpipes: For the low pressure system, a, specially designed injector type blowpipe is required,, which may be used for high pressure system also., In the high pressure system, a mixer type high pressure, blowpipe is used which is not suitable for the low pressure, system., Dissolved acetylene (acetylene in cylinder) is the commonly used source, Acetylene generated from a high pressure generator is, not commonly used., A low pressure plant utilizes acetylene under low pressure(0.017 kg/cm)produced by the acetylene generator, only.(Fig 2), High pressure and low pressure plants utilize, oxygen gas kept in compressed high pressure, cylinders only at 120 to 150 kg/cm pressure., Oxy-acetylene systems: A high pressure oxy-acetylene, plant is also called a high pressure system., A low pressure acetylene plant with a low pressure acetylene, generator and a high pressure oxygen cylinder is called a, low pressure system., , To avoid the danger of high pressure oxygen entering into, the acetylene pipeline an injector is used in a low pressure, blowpipe. In addition a non-return valve is also used in the, blowpipe connection on the acetylene hose. As a further, precaution to prevent the acetylene generator from exploding,, a hydraulic back pressure valve is used between the, acetylene generator and the blowpipe., Advantages of high pressure system: Safe working and, less chances of accidents. The pressure adjustment of, gases in this system is easy and accurate, hence working, efficiency is more. The gases being in cylinder are perfectly, under control. The D.A cylinder is portable and can be, taken easily from one place to another place., The D.A cylinder can be fitted with a regulator quickly and, easily, thus saving time.Both injector and non-injector type, blowpipes can be used. No license is required for keep the, D.A cylinder., Sequence of steps, Slowly open the cylinder valve., Open the shut-off valve or pressure reducing valve, Open the valve on torch., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 241
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Slowly screw in the adjusting screw. (The locking bolt, opens.), Watch the working pressure gauge., Turn the adjusting screw until the desired pressure is, reached. There is an equilibrium between the bottom, adjusting spring and the pressure of the gas on the, membrane, which is amplified by the spring of the locking, pin., Care and maintenance of regulators, Check the cylinder connection and crack the cylinder, before fixing the regulator. (Fig 3), , Do not wind the hose on the regulators (Fig 6), , Use hose-clips before connecting to the regulator., Open the cylinder valve slowly and allow the gas to pass, to the regulator (cylinder) content gauge., Loosen the pressure screw., , Use soap water to check the leakage in the acetylene, regulator connections and plain water on the oxygen relator, connections. Fig7, , Do not use oil in regular connections. (Fig 4), , Do not fix the oxygen and acetylene regulators close, together (Fig 5), , 242, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Gas welding torch its type and construction, Objectives : At the end of this lesson you shall be able to, • State the uses of the different types of blowpipes, • describe the working principle of each type of blowpipe, • explain its care and maintenance., Types, There are two types of blowpipes., High pressure blowpipe or non-injector bype blowpipe, Low pressure blowpipe or injector type blowpipe., Uses of blow pipes: Each type consists of a variety of, designs depending on the work for which the blowpipe is, required. i.e gas welding, brazing,very thin sheet welding,, heating before and after welding, gas cutting., , The equal pressure blow pipe (Fig.1) consists of two inlet, connections for acetylene and oxygen gases kept in high, pressure cylinders. Two control valves to control the, quantity of flow of the gases and a body inside which the, gases are mixed in the mixing chamber (Fig 2). The mixed, gases flow through a neck pipe to the nozzle and then get, ignited at the tip of the nozzle. Since the pressure of the, oxygen and acetylene gases are set at the same pressure, of 0.15 kg/cm2 they mix together at the mixing chamber, and flows through the blow pipe to the nozzle tip on its, own.This equal pressure blow pipe/torch is also called as, high pressure blow pipe/torch because this is used in the, high pressure system of gas welding., , Equal or High pressure blowpipe (Fig 1): The H.P., blowpipe is simply a mixing device to supply approximately, equal volume of oxygen and acetylene to the tip, and is, fitted with valves to control the flow of the gases as required., i.e the blow pipes/ gas welding torches are used for welding, of ferrous and non-ferrous metals, joining thin sheets by, fusing the edges, preheating and post heating of jobs,, brazing, for removing the dents formed by distortion and for, gas cutting using a cutting blow pipe., , Low pressure blowpipe (Fig 3), This blowpipe has an injector (Fig 3) inside its body through, which the high pressure oxygen passes. This oxygen, draws the low pressure acetylene from an acetylene, generator into a mixing chamber and gives it the necessary, velocity to get a steady flame and the injector also helps, to prevent backfiring., The low pressure blow pipe is similar to the equal pressure, blow pipe except that inside its body an injector with a very, small (narrow) hole in its centre through which high, pressure oxygen is passed. This high pressure oxygen, while coming out of the injector creates a vaccuum in the, mixing chamber and sucks the low pressure acetylene, from the gas generator (Fig.4), It is usual for the whole head to be interchangeable in this, type, the head containing both the nozzle and injector.This, is necessary, since there is a corresponding injector size, for each nozzle., , A set of nozzles is supplied with each blowpipe, the, nozzles having holes varying in diameters, and thus giving, various sized flames. The nozzles are numbered with their, consumption of gas in litres per hour., , The L.P. blowpipe is more expensive than the, H.P. blowpipe but it can be used on a high, pressure system, if required., , Important caution: A high pressure blowpipe, should not be used on a low pressure system., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 243
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Care and maintenance, Welding tips made of copper may be damaged by careless, handling., Nozzles should never be dropped or used for moving or, holding the work., The nozzle seat and threads should be absolutely free from, foreign matter in order to prevent any scoring/scratch on, the fitting surfaces when tighening on assembly., The nozzle orifice should only be cleaned with a tip cleaner, specially designed for this purpose. (Fig 5, 6 & 7), , At frequent intervals the nozzle tip should be filed to remove, any damage to the tip due to the excessive heat of the flame, and the molten metal., The inlet for acetylene has left hand thread and that for, oxygen has right hand thread. Take care to fit the correct, hose pipe with the blow pipe inlet. At frequent intervals, put, off the flame and dip the blow pipe in cold water., , 244, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Types of welding joints (butt and fillet), Objectives: At the end of this lesson you shall be able to, • illustrate and name the basic welding joints, • explain the nomenclature of butt and fillet welds., Basic welding joints (Fig 1), The various basic welding joints are shown in Fig 1., The above types mean the shape of the joint, that is, how, the joining edges of the parts are placed together., , Types of weld: There are two types of weld.(Fig 2), – Groove weld/butt weld, – Fillet weld, , Nomenclature of butt and fillet weld (Figs 3 and 4), , Reinforcement: Metal deposited on the surface of the, parent metal or the excess metal over the line joining the, two toes. (Fig 6), , Root gap: It is the distance between the parts to be joined., (Fig 3), Heat affected zone: Metallurgical properties have been, changed by the welding heat adjecent to weld., Leg length: The distance between the junction of the, metals and the point where the weld metal touches the, base metal ‘ toe’. (Fig 5), Parent metal: The material or the part to be welded., Fusion Penetration: The depth of fusion zone in the, parent metal.(Fig.3 and 4), , Root: The parts to be joined that are nearest together., (Fig 7), , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 245
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Root face: The surface formed by squaring off the root, edge of the fusion face to avoid a sharp edge at the root., (Fig 8), , Backing run: A small weld deposited on the root side of, the butt or corner joint (before welding the joint).Fig.6, Throat thickness: The distance between the junction of, the metals and the midpoint on the line joining the two, toes.(Fig 5), Toe of weld: The point where the weld face joins the parent, metal.(Fig 5 & 6), , Root run: The first run deposited in the root of a joint., (Fig 9), , Weld face: The surface of a weld seen from the side from, which the weld was made.(Fig 5 & 6), Weld junction: The boundary between the fusion zone, and the heat affected zone.(Fig.3 & 4), Fusion face: The portion of a surface which is to be fused, on making the weld.(Fig 11), , Root penetration: It is the projection of the root run at the, bottom of the joint (Fig.6 and 9), , Fusion zone: The depth to which the parent metal has, been fused. (Fig 11), , Run: The metal deposited during one pass.Fig.9., The second run is marked as 2 which is deposited over the, root run. The third run is marked as 3 which is deposited, over the second run., Sealing run: A small weld deposited on the root side of a, butt or corner joint (after completion of the weld joint)., (Fig 10), , 246, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Purpose of root gap, tacking and key hole in the weld joint during welding, Objectives: At the end of this lesson you shall be able to, • explain the purpose of the root gap kept in the joint before welding, • state the purpose of tacking the job pieces before welding and state the importance of key hole during, welding., Gap: root gap or root opening in welding joints, Before welding, the joining parts of the assembly are kept, apart for some specific distance. (Fig 1) This distance is, called root gap or root opening., , Purpose: The purpose is to obtain the required depth of, fusion or complete penetration to the entire depth of the, joint during welding. (Fig 2), , For intermediate tack welds the length should be between, two and three times the plate thickness, up to a maximum, length of 35mm., The arc has a limitation. It melts only to a certain depth in, the base metal. This limit is equal to or less than the, diameter of the electrode used. So if root gap is not given, the base metal may not be fused till the bottom of the joint., So root gap is essential while welding., Tack welds: A tack weld is a short weld used to help, assembly and to maintain the position of parts during, welding., Tack welds should be between three and four times the, plate thickness, upto a maximum length of 35mm at the, ends of the joint. (Fig 3 and 4), , Pitch of tack welds: For mild steel plates of 3mm thickness, the pitch (i.e. distance between centres) of tack, welds in butt joints should be 150mm. The pitch should be, increased by about 15mm for each 1mm increase in plate, thickness, upto maximum of 600mm for thicknesses of, 33mm and above., For lengths less than twice the normal pitch distance, end, tack welds only are required. The above pitch distances, should be doubled for fillet-welded T-joints., Tack welds are done on the rear side of the, joint and not on the welding side. (Fig.3 and 4), Purpose: To maintain the root gap and alignment of the, assembly parts and for controlling of distortion during, welding, tacking is necessary. (Fig 5), , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 247
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It is created to obtain complete penetration without excessive melt through., , Importance of keyhole during welding: Keyhole is one, of the product of welding technique while welding single run, weld (corner & butt) or root run in corner and Vee groove, welds., , A key-hole can be produced by the correct combination of, welding current, electrode angles, arc travel speed, electrode motions and arc length. The diameter of the key hole, can be slightly (i.e 1mm) more than the root gap. An, enlarged key hole will cause a burn through defect., , It is a little hole (like a keyhole) at the leading edge of the, crater right under the tip of the electrode.(Fig.6), , Edge preparation, Objectives: At the end of this lesson you shall be able to, • explain the necessity of edge preparation, • describe the edge preparation for butt and fillet welds., Necessity of edge preparation: Joints are prepared to, weld metals at less cost. The preparation of edges are also, necessary prior to welding in order to obtain the required, strength to the joint. The following factors are to be taken, into consideration for the edge preparation., – The welding process like SMAW, oxy-acetylene welds,, Co2, electro-slag etc., – The type of metal to be jointed, (i.e.) mild steel,, stainless steel, aluminium, cast iron etc., – The thickness of metal to be joined., – The type of weld (groove and fillet weld), – Economic factors, The square butt weld is the most economical to use, since, this weld requires no chamferring, provided satisfactory, strength is attained. The joints have to be bevelled when the, parts to be welded are thick so that the root of the joints, have to be made accessible for welding in order to obtain, the required strength., , 248, , In the interest of economy, bevel butt welds should be, selected with minimum root opening and groove angles, such that the amount of weld metal to be deposited is the, smallest. "J" and "U" butt joints may be used to further, minimise weld metal when the savings are sufficient to, justify the more difficult and costly chamferring operations., The "J" joint is usually used in fillet welds., A root gap is recommended since the spacing allows the, shrinking weld to draw the plates freely together in the butt, joint. Thus, it is possible to reduce weld cracking and, minimise distortion and increase penetration, by providing, a root gap for some welded joints., Method of edge preparation: The joining edges may be, prepared for welding by any one of the methods mentioned, below., – Flame cutting, – Machine tool cutting, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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– Machine grinding or hand grinding, – Filing, chipping, Types of edge preparation and setup, Different edge preparations generally used in arc welding, are shown in Fig 1 below., , Basic welding joints and position, Objectives : At the end of this lesson you shall be able to, • name the basic welding joints from drawings, • state the basic welding positions from drawings., Basic welding joints (Fig 1), , Basic welding positions (Fig 2), , The following are the basic welding joints., , The following are the important basic welding positions, , -, , Butt joint, , -, , Flat or downhand position, , -, , Lap joint, , -, , Horizontal position, , -, , Tee joint, , -, , Vertical position, , -, , Corner joint, , -, , Overhead position, , -, , Edge joint, , The above types indicate the shape of the joints and how, the joining edges of parts are placed together. (Joint, designs are very important in fabrication work)., , Welding action takes place in the molten pool,formed in the, welding joint or the welding line., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 249
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The position of the welding joint line in respect of the ground, axis indicates the welding position., All joints can be welded in all positions., , Gases and gas cylinders description, kinds, main difference and uses, Objectives: At the end of this lesson you shall be able to, • name the different types of gases used in gas welding, • state the different types of gas flame combinations, • state the temperatures and uses of the different gas flame combinations., In the different gas welding processes, the welding heat is, obtained from the combustion of the fuel gases., , -, , Acetylene gas, , -, , Hydrogen gas, , All the fuel gases require oxygen to support combustion., , -, , Coal gas, , -, , Liquid petroleum gas (LPG), , As a result of the combustion of the fuel gases and oxygen,, a flame is obtained. This is used to heat the metals for, welding. (Fig 1), , Supporter of combustion gas, All gases burn with the help of oxygen. Hence it is known, as the supporter of combustion., Different gas flame combinations, Oxygen + Acetylene = Oxy - Acetylene gas flame, Oxygen + Hydrogen = Oxy - Hydrogen gas flame, Oxygen + Coal = Oxy - coal gas flame, Oxygen + LPG = Oxy - LP gas flame, Temperature and uses of gas flame combinations, Oxy-acetylene gas flame (Fig 2), Flame temperature : 3100° C to 3300° C, , Fuel gases used in welding, The following are the gases used as fuel for welding., , 250, , The Oxy - Acetylene gas flame is used for welding all, ferrous and non-ferrous metals and their alloys, gas cutting,, gouging, steel brazing, bronze welding, metal spraying, and powder spraying., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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This flame has carbon and moisture effect., It is only used for gas cutting of steel, and for heating., , Oxy - Hydrogen gas flame (Fig 3), Flame temperature : 2400°C to 2700°C, , Oxy-coal gas flame (Fig 5), , It has carbon and moisture effect in the flame. It is used, only for brazing, silver soldering and underwater gas cutting, of steel., Oxy-liquid petroleum gas flame (Fig 4), Flame temperature : 2700°C to 2800°C, , Flame temperature : 1800°C to 2200°C, This flame has carbon effect in the flame and is used for, silver soldering and brazing., The most commonly used gas flame, combination is OXY - ACETYLENE., , Oxygen gas cylinder, Objectives: At the end of this lesson you shall be able to, • name different gas cylinders, • explain the constructional features of oxygen gas cylinder and the method of charging., Definition of a gas cylinder: It is a steel container, used, to store different gases at high pressure safely and in large, quantity for welding or other industrial uses., , Types and identifications of gas cylinders: Gas, cylinders are called by names of the gas they are, holding. (Table 1), , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 251
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Table 1, Identification of gas cylinders, Name of gas, cylinder, , Colour, coding, , Valve, threads, , Oxygen, Acetylene, Coal, , Black, Maroon, Red (with, name coal gas), Red, Grey (with, black neck), Grey, Red (with, larger diameter and name, propane), Blue, Black (with, white neck), , Right hand, Left hand, Left hand, , Hydrogen, Nitrogen, Air, Propane, , Argon, Carbon-dioxide, , It is made from seamless solid drawn steel and tested with, a water pressure of 225kg/cm2. The cylinder top is fitted, with a high pressure valve made from high quality forged, bronze. (Fig 2), , Left hand, Right hand, Right hand, Left hand, , Right hand, Right hand, , Gas cylinders are identified by their body colour marks and, valve threads. (Table 1), Oxygen gas cylinder: It is a seamless steel container, used to store oxygen gas safely and in large quantity under, a maximum pressure of 150 kg/cm2, for use in gas welding, and cutting., Constructional features of oxygen gas cylinder (Fig 1), , The cylinder valve has a pressure safety device, which, consists of a pressure disc, which will burst before the, inside cylinder pressure becomes high enough to break, the cylinder body. The cylinder valve outlet socket fitting, has standard right hand threads, to which all pressure, regulators may be attached. The cylinder valve is also fitted, with a steel spindle to operate the valve for opening and, closing. A steel cap is screwed over the valve to protect it, from damage during transportation. (Fig 1), The cylinder body is painted black., The capacity of the cylinder may be 3.5m3– 8.5m3., Oxygen cylinders of 7m3 capacity are commonly used., Charging of gas in oxygen cylinder: The oxygen, cylinders are filled with oxygen gas under a pressure of, 120-150 kg/cm2. The cylinders are tested regularly and, periodically. They are annealed to relieve stresses caused, during ‘on the job’ handling. They are periodically cleaned, using caustic solution., , 252, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Dissolved acetylene gas cylinder, Objectives: At the end of this lesson you shall be able to, • describe the constructional features of the DA gas cylinder and the method of charging, • state the safety rules for handling gas cylinders, • explain the safe procedure to be followed in handling an internally fired DA cylinder., Definition: It is a steel container used to store high, pressure acetylene gas safely in dissolved state for gas, welding or cutting purpose., Constructional features (Fig 1): The acetylene gas, cylinder is made from seamless drawn steel tube or, welded steel container and tested with a water pressure of, 100kg/cm2 The cylinder top is fitted with a pressure valve, made from high quality forged bronze. The cylinder valve, outlet socket has standard left hand threads to which, acetylene regulators of all makes may be attached. The, cylinder valve is also fitted with a steel spindle to operate, the valve for opening and closing. A steel cap is screwed, over the valve to protect it from damage during transportation., The body of the cylinder is painted maroon. The capacity, of the D A cylinder may be 3.5m3–8.5m3., , Method of charging D A gas cylinder: The storage of, acetylene gas in its gaseous form under pressure above, 1kg/cm2 is not safe. A special method is used to store, acetylene safely in cylinders as given below., The cylinders are filled with porous substances such as:, – pith from corn stalk, – fullers earth, – lime silica, – specially prepared charcoal, – fibre asbestos., The hydrocarbon liquid named acetone is then charged in, the cylinder, which fills the porous substances (1/3rd of, total volume of the cylinder)., Acetylene gas is then charged in the cylinder, under a, pressure of app.15 kg/cm2., , The base of the D A cylinder (curved inside) is fitted with, fuse plugs which will melt at a temperature of app. 100°C., (Fig 2) In case the cylinder is subjected to high temperature,, the fuse plugs will melt and allow the gas to escape, before, the pressure increases enough to harm or rupture the, cylinder. Fuse plugs are also fitted on the top of the, cylinder., , The liquid acetone dissolves the acetylene gas in large, quantity as safe storage medium; hence, it is called, dissolved acetylene. One volume of liquid acetone can, dissolve 25 volumes of acetylene gas under normal, atmospheric pressure and temperature. During the gas, charging operation one volume of liquid acetone dissolves, 25x15=375 volumes of acetylene gas under 15kg/cm2, pressure at normal temperature. While charging cold water, will be sprayed over the cylinder so that the temperature, inside the cylinder does not cross certain limit., , Safety rules for gas cylinders, Oxy-acetylene equipment is safe if it is properly, handled, but it may become a great destructive, power if handled carelessly. It is important that, the operator be familiar with all the safety rules, before handling gas cylinders., Keep the cylinders free of oil, grease or any type of, lubrication., , Check leakage before use., Open cylinder valves slowly., Never fall or trip over gas cylinders., A valve broken in the oxygen cylinder will cause, it to become a rocket with tremendous force., , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence, , 253
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Keep the gas cylinders away from exposure to high, temperature., Remember the pressure in the gas cylinders, increases with the temperature., Store full and empty gas cylinders separately in a well, ventilated place., Mark the empty cylinders (MT/EMPTY) with chalk ., If a cylinder leaks due to defective valve or safety plug, do, not try to repair it yourself, but move it to a safe area with, a tag to indicate the fault and then inform the supplier to, pick it up., , Safety procedure for handling an internally fired, dissolved acetylene (D A ) cylinder, In the case of severe backfire or flashback the D A cylinder, may catch fire., Close the blowpipe valve immediately (oxygen first)., No damage will occur to the cylinder if the backfire is, arrested at the blowpipe., The signs of severe backfire or flashback are:, – a squealing or hissing noise in the blowpipe, – a heavy black smoke and sparks coming out of the, nozzle, – overheating of the blowpipe handle., , When the cylinders are not in use or they are being moved,, put on the valve protection caps., Cylinders should always be kept in upright position and, properly chained when in use., Close the cylinder valves both when they are full or empty., Never remove the valve protection cap while lifting cylinders., Avoid exposing the cylinders to furnace heat, open fire or, sparks from the torch., Never move a cylinder by dragging, sliding or rolling it on its, sides., Never apply undue force to open or close a, cylinder valve., Avoid the use of hammer or wrench., Always use a proper cylinder (or spindle) key to open or, close the cylinder valves., Do not remove the cylinder key from the cylinder valve when, it is in use. It may be needed immediately to close the gas, in case of emergency., Smoking or naked lights should be strictly, prohibited near gas cylinders., , To control this:, – close the cylinder valves, – disconnect the regulator from the cylinder valve, – check the hosepipes and blowpipe before re-use., If the cylinder catches fire externally due to the leakage of, gas at the connection:, – close the cylinder valve immediately (wearing asbestos, gloves as a safety measure), – use carbon dioxide fire extinguisher to extinguish the, fire, – rectify the leakage thoroughly before putting into further, use., If the cylinder becomes overheated due to internal or, external fire:, – close the cylinder valve, – detach the regulator from the cylinder, – remove the cylinder to an open space, away from, smoking or naked light, – cool the cylinder by spraying with water, – inform the gas cylinder supplier immediately., Never keep such defective cylinders with the, other cylinders., , Never strike an arc or direct gas flame on a gas cylinder., , 254, , P&M : Fitter - Related Theory for Exercise 1.4.57 & 1.4.58, , Copyright Free Under CC BY Licence
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Production & Manufacturing, Fitter - Welding, , Related Theory for Exercise 1.4.59, , Setting up parameter for arc welding machine, Objectives: At the end of this lesson you shall be able to, • select and set the electrode and current according to the plate thickness., Electrode size and AMPS used, The following will serve as a basic guide of the amp range, that can be used for different size electrodes. Note that, these ratings can be different between various electrode, manufactures for the same size rod. Also the type coating, on the eletrode could effect the amperage range. When, possible, check the manufactures info of the electrode you, wil be using for their recommended amperage settings., , Electrode Table, Electrode, , AMP, , Plate, , 1/16", , 20 - 40, , Up to 3/16", , 3/32", , 40 - 125, , Up to 1/4", , 1/8, , 75 - 185, , Over 1/8", , 5/32", , 105 - 250, , Over 1/4", , 3/16", , 140 - 305, , Over 3/8", , 1/4", , 210 - 430, , Over 3/8", , 5/16", , 275 - 450, , Over 1/2", , Note : The thicker the material to be welded,, the higher the current needed and the larger, the electrode needed., , 255, , Copyright Free Under CC BY Licence
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Arc welding electrodes, Objectives: At the end of this lesson you shall be able to, • explain arc welding electrode, • state the types of electrodes, • explain the coating factor, • describe the characteristics of flux coating on electrode, • explain the functions of flux coating during welding., Introduction: An electrode is a metallic wire of standard, size and length, generally coated with flux (may be bare or, without flux coating also) used to complete the welding, circuit and provide filler material to the joint by an arc,, maintained between its tip and the work. (Fig 1), , Different types of electrodes used are given in the Electrode, chart., 1.6 to 2.2 for heavy coated, and above 2.2 for super heavy, coated electrodes., , Method of flux coating:, – Dipping, , Types of flux coating, , – Extrusion, – Cellulosic, Dipping method: The core wire is dipped in a container, carrying flux paste. The coating obtained on the core wire, is not uniform resulting in non-uniform melting; hence this, method is not popular., Extrusion method: A straightened wire is fed into an, extrusion press where the coating is applied under pressure., The coating thus obtained on the core wire is uniform and, concentric, resulting in uniform melting of the electrode., (Fig 2) This method is used by all the electrode, manufacturers., Coating factor (Fig 3): The ratio of the coating diameter to, the core wire diameter is called the coating factor., Coating factor =, , Coating dia of electrode, Core wire dia. of electrode, , It is 1.25 to 1.3 for light coated,, 1.4 to 1.5 for medium coated,, , 256, , – Rutile, – Iron powder, – Basic coated, Cellulosic electrode: Cellulosic electrode coatings are, made of materials containing cellulose, such as wood pulp, and flour. The coating on these electrodes is very thin and, the slag in easily removed from deposited welds. The, coating produces high levels of hydrogen and is therefore, not suitable for high-strength steels. This type of electrode, is usually used on DC+ and suited to vertical down welding., Rutile electrodes: Rutile electrodes, are general-purpose, electrodes have coatings based on titanium dioxide. These, electrodes are widely used in the fabrication industry as, they produce acceptable weld shape and the slag on, deposited welds is easily removed. Strength of deposited, welds is acceptable for most low-carbon steels and the, majority of the electrodes in this group are suitable for use, in all positions., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence
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Basic or hydrogen-controlled electrodes: Basic or, hydrogen controlled electrode coatings are based on, calcium fluoride or calcium carbonate. This type of electrode, is suitable for welding high-strength steels without weld, cracks and the coatings have to be dried. This drying is, achieved by backing at 4500C holding at 3000C and storing, at 1500C until the time of use. By maintaining these, conditions it is possible to achieve high strength weld, deposits on carbon, carbon manganese and low alloyed, steels. Most electrodes in this group deposit welds with, easily removable slags, producing acceptable weld shape, in all positions. Fumes given off by this electrode are, greater than with other types of electrodes., , Binding and plasticizing substances: These substances, help the applied coating to grip firmly around the core wire, of the electrode., , Iron powder electrodes: Iron powder electrodes get their, name from the addition of iron powders to the coating which, tend to increase efficiency of the electrode. For example,, if the electrode efficiency is 120%, 100% is obtained from, the core wire and 20% from the coating. Deposited welds, are very smooth with an easily removable slag; welding, positions are limited to horizontal, vertical fillet welds and, flat or gravity position fillet and butt welds., , – It compensates the losses of certain elements which, are burnt out during welding., , Composition/characteristics flux: The coating of the, welding electrodes consists of a mixture of the following, substances., Alloying substances: These substances compensate for, the burning of manganese, ferro-silicon. The alloying, substances are:, , These are sodium and potassium silicates., Purpose or function of flux coating: During welding,, with the heat of the arc, the electrode coating melts and, performs the following functions., – It stabilizes the arc., – It forms a gaseous shield around the arc which protects, the molten weld pool from atmospheric contamination., , – It retards the rate of cooling of the deposited metal by, covering with slags and improves its mechanical, properties., – It helps to give good appearance to the weld and, controls penetration., – It makes the welding in all positions easy., – Both AC and DC can be used for the welding., – Removes oxide, scale etc. and cleans the surfaces to, be welded., – It increases metal deposition rate by melting the, additional iron powder available in the flux coating, , – ferro-manganese, , Types of electrodes for ferrous and alloy metals, , – ferro-silicon, – ferro-titanium., , Mild steel electrode: Mild steel is characterized by, carbon content not exceeding 0.3%. Mild steel electrode, core wire contains various alloying elements., , Arc stabilising substances: These are carbonates known, as chalk and marble. These are used for the stabilisation, of the arc., , Carbon 0.1 to 0.3%, (Strengthening agent), , Deoxidizers: These substances prevents porosity and, make the welds stronger. The deoxidising substances are, iron oxide, lamitite, magnetite., Slag forming substances: These substances melt and, floats over the molten metal and protect the hot deposited, weld metal from the atmospheric oxygen and nitrogen., Also due to the slag covering the weld metal is prevented, from fast cooling. The slag forming substances are clay,, limestone., Fluxing/cleaning substances: These substances remove, oxides from the edges to be welded and controls the fluidity, of the molten metal. The cleaning substances are lime, stone, chlorides, fluorides., Gas forming substances: These substances form gases, which aid the transfer of metal. They also shield the welding, arc and weld pool. The substances are wood flour dixtorine, and cellulose., , Keep carbon as low as possible., Silicon above 0.5%, (Deoxidizes, prevents weld metal porosity.), Manganese 1.65%, (Increases strength and hardness.), Nickel, (Increases strength and notch toughness.), Chromium, (Increases tensile strength and hardness. Lowers the, ductility.), Molybdenum 0.5%, (Increases hardness and strength.), Indian Standard System laid down in IS:814-1991 a, classification and coding of covered electrodes for metal, arc welding of mild steel, and low alloy high tensile steel., Mild steel and low alloy high tensile steel electrodes are, classified into seven recognised groups, depending upon, , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 257
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the chemical composition of the flux coating., , by the burning of the cellulosic materials in the flux coating., , Stainless steel electrodes: Selecting proper electrodes, depends primarily on the composition of the base metal to, be welded., , Butt joints on heavy sections are welded without edge, preparation using these electrodes., , These electrodes are available with either lime or titanium, coatings. The lime coated electrode is used only with DC, reverse polarity. Titanium coated electrodes can be used, in AC and DC reverse polarity, and will produce smoother, and stable arc., The coding system for stainless steel electrodes differs, somewhat from that for the M.S. electrode. The I.S.5206 1969 specification for corrosion-resisting chromium and, chromium-nickel steel covered electrodes will give full, details., During welding, the electrode will tend to get red hot, quickly. To avoid this, 20 to 30% lower current than what, is used for ordinary M.S. electrode is recommended., Special purpose electrodes:, – Deep penetration electrodes, – Contact electrodes or iron powder electrodes, – Cutting and gouging electrodes, – Underwater welding and cutting electrodes, – Low hydrogen electrodes., Deep penetration electrodes: These electrodes are, used to get deep penetration in the joints. Deep penetration, occurs because of the very strong stream of gas produced, , The depth of the penetration will be more than to the core, wire diameter of the electrode used., Contact electrodes (Iron powder): These electrodes contain, a large amount of iron powder in their coatings. Therefore, the arc ignites very easily. These electrodes are also, called ‘touch type’ electrodes. While using this type of, electrodes a large amount of weld metal is deposited per, unit time., Cutting and gauging electrodes: The cutting electrodes, are of a tubular type. While cutting, air is sent through the, centre at high pressure to cut ferrous metals. The gouging, electrodes can make ‘U’ grooves on the ferrous metals., Underwater welding and cutting electrodes: These, electrodes are used to cut and weld metals under the, water. The coating having an external coating of varnish by, ‘lacquer’ polishing or ‘celluloid ‘ helps to insulate and, protect the electrodes when immersed in water for welding, or cutting purpose., Low hydrogen electrodes: Hydrogen controlled, electrodes shall be such that the diffusible hydrogen, content of the deposited metal will be low. This electrode, is used with DC reverse polarity and can be used in all, welding positions. These electrodes help to get a weld, without cracks., , Coding of electrodes, Objectives: At the end of this lesson you shall be able to, • explain the necessity of coding electrodes, • describe the electrode coding as per BIS, AWS and BS., Necessity of coding electrodes: Electrodes with different flux covering gives different properties to the weld metal., Also electrodes are manufactured suitable for welding with, AC or DC machines and in different positions. These, conditions and properties of the weld metal can be interpreted by the coding of electrodes as per Indian Standards., The chart shown at the end of this lesson gives the, specification of a particular electrode and also shows what, each digit and letter in the code represents. By referring to, this chart any one can know whether an electrode with a, given specification can be used for welding a particular job, or not., Classification of electrodes shall be indicated by the IS:, 814-1991 coding system of letters and numerals to indicate the specified properties or characteristics of the, electrode., , 258, , Main coding: It consists of the following letters and, numerals and shall be followed in the order stated:, a) a prefix letter ‘E’ shall indicate a covered electrode for, manual metal arc welding, manufactured by extrusion, process;, b) a letter indicating the type of covering;, c) first digit indicating the ultimate tensile strength in, combination with the yield stress of the weld metal, deposit;, d) second digit indicating the percentage elongation in, combination with the impact values of the weld metal, deposited;, e) third digit indicating welding position(s) in which the, electrode may be used and, f) fourth digit indicating the current condition in which the, electrode is to be used., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence
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Additional coding: The following letters indicating the, additional properties of the electrodes may be used, if, required:, a) letters H1, H2, H3 indicating hydrogen controlled electrodes, b) letters J, K and L indicating increased metal recovery as, ‘Effective Electrode Efficiency’ as per IS:13043:91., Specification in the followings range:, J = 110 - 129 percent;, K = 130 - 149 percent; and, L = 150 percent and above., , Table 2, Combination of percentage elongation and, impact strength, (Clause 5.3), Designation Percentage elondigit, gation (Min) on, 5.65/So, , Impact strength, in joules, (Min)/at °C, , (For tensile range 410-510 N/mm2 ), , c) letter ‘X’ indicating the radiographic quality, Different standards used in coding of electrodes, They are:, , 0, , No elongation and impact requirements, , 1, 2, 3, 4, , 20, 22, 24, 24, , 47J/+27°C, 47J/+0°C, 47J/-20°C, 27J/-30°C, , (For tensile range 510-610 N/mm2), , 1 I.S. (814 - 1991), 2 A.W.S., 3 B.S., Indian system of coding of electrodes according to IS : 8141991, Type of covering: The type of covering shall be indicated, by the following letters., , 0, , No elongation and impact requirements, , 1, 2, 3, 4, 5, 6, , 18, 18, 20, 20, 20, 20, , 47J/+27°C, 47J/+0°C, 47J/-20°C, 27J/-30°C, 27J/-40°C, 27J/-46°C, , Welding position: The welding position or positions in, which the electrode can be used as recommended by the, manufacturer shall be indicated by the appropriate designating digits as follows., , A, , - Acid, , B, , - Basic, , C, , - Cellulosic, , R, , - Rutile, , 1 All positions, , RR, , - Rutile, heavy coated, , 2 All positions except vertical down, , S, , - Any other type not mentioned above, , 3 Flat butt weld, flat fillet weld and horizontal/vertical fillet, weld, , Strength characteristics: The combination of the ultimate tensile strength and the yield strength of the weld, metal deposited shall be indicated by the digits 4 and 5., (See Table 1.), , Designation of strength characteristics, (Clauses 5.2 and 5.3), , 4, 5, , Ultimate tensile, strength, N/mm2, 410-510, 510-610, , 5 Vertical down, flat butt, flat fillet and horizontal and, vertical fillet weld, 6 Any other position or combination of positions not, classified above, , Table 1, , Designating, digit, , 4 Flat butt weld and flat fillet weld, , Yield strength, Min, N/mm2, 330, 360, , Elongation and impact properties: The combination of, percentage elongation and impact properties of all weld, metal deposited for the two tensile ranges (See Table 1), shall be as given in Table 2., , Where an electrode is coded as suitable for vertical and, overhead position it may be considered that sizes larger, than 4 mm are not normally used for welding in these, positions., An electrode shall not be coded as suitable for a particular, welding position unless it is possible to use it satisfactorily, in the position to comply with test requirements of this, code., Welding current and voltage conditions: The welding, current and open circuit voltage conditions on which the, electrodes can be operated as recommended by the, manufacturer shall be indicated by the appropriate designating digits as given in Table 3., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 259
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For the purpose of coding an electrode, for any of the, current conditions under 5.5 shall be of size 4 mm or 5 mm, and shall be capable of being operated at that condition, satisfactorily within the current range recommended by the, manufacturer., , 1 Symbol 0 reserved for electrodes used exclusively on, direct current,, 2 Positive polarity +, Negative polarity –., The frequency of the alternating current is assumed to be 50 or 60 Hz. The open circuit voltage, necessary when electrodes are used on direct, current is closely related to the dynamic characteristics of the welding power source. Consequently no indication of the minimum open circuit voltage for direct current is given., , Hydrogen controlled electrodes: The letters H1, H2 and, H3 shall be included in the classification as a suffix for those, electrodes which will give diffusible hydrogen per 100 gm, when determined in accordance with the reference method, given in IS: 1806:1986 as given below., H1 H2 H3 -, , Up to 15 ml diffusible hydrogen, Up to 10 ml diffusible hydrogen, Up to 5 ml diffusible hydrogen, , Welding current and voltage conditions, (Clause 5.5), , Increased metal recovery: The letters J, K and L shall be, included in the classification as a suffix for those electrodes which have appreciable quantities of metal powder, in their coating and give increased metal recovery with, respect to that of core wire melted, in accordance to the, range given in 5.0.2 (b)., , Digit Direct current: recommended Alternating, electrode polarity, current: open, circuit voltage,, V, Min, , The metal recovery shall be determined as ‘Effective, Electrode Efficiency (E E) as per the method given in IS, 13043:1991., , Table 3, , 0, , –, , 1, 2, 3, 4, 5, 6, 7, 8, 9, , + or –, –, +, + or –, –, +, + or –, –, +, , Not, recommended, 50, 50, 50, 70, 70, 70, 90, 90, 90, , Radiographic quality electrodes: The letter ‘X’ shall be, included in the classification as a suffix for those electrodes which deposit radiographic quality welds., , Example 1, The classification for the electrode EB 5426H1JX, E, , B, , 5, , 4, , 2, , 6, , Covered electrode, Type of covering (Basic), Strength characteristics (UTS=510–610 N/mm2 and, YS = 360 N/mm2 min.), Elongation and impact properties (Elongation =20% min. and, IMPACT = 27 J min. at – 300 C), Welding position (all positions except vertical down), Welding current and voltage condition (D + and A 70), Hydrogen controlled electrodes (15 ml max.), Increased metal recovery, , (110 – 129%), , Radiographic quality electrode, 260, , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , H1, , J, , X
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Example 2, The classification for the electrode ER 4211, E, , R, , 4, , 2, , 1, , 1, , Covered electrode, Type of covering (Rutile), Strength characteristics (UTS = 410 – 510 N/mm2, and YS = 330 N/mm2 min.), Elongation and impact properties (Elongatiion = 22 % min. and, impact = 47 J min. at 00 C), Welding position, , (all positions), , Welding current and voltage conditiions (D ± and A 50), AWS codification of carbon steel and low alloy steel, coated electrodes, , The first two digits indicate tensile strength and yield, stress., , Chart - 1 shows the details of AWS coding of an electrode., , The next two digits indicate elongation and impact strength., , In the chart , E stands for electrode. It means that it is, a stick electrode., , The letter after the first 4 digits indicates the type of, covering., , The first two digits are very important. They designate the, minimum tensile strength of the weld metal that the, electrode will produce., , The first 3 digits after the letter indicating the type of, covering shows electrode efficiency., , The third digit indicates the welding positions., , The fourth digit after the letter indicating the type of covering, shows the welding position., , The last digit in the code indicates the kind of flux coating, used., , The fifth digit after the letter indicating the type of covering, indicates current and voltage., , BS codification of carbon steel and low alloy steel, covered electrodes (BS 639 : 1976 equivalent to ISO, 2560), , In the case of rutile covered electrodes, the digits indicating, the electrode efficiency after the letter indicating the types, of covering will not be given as shown in chart 1., , As shown in chart 2, E stands for covered MMA electrode., , Chart 2 shows an electrode coding with electrode efficiency., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 261
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CHART 1, AWS CODIFICATION OF CARBON STEEL AND LOW-ALLOY STEEL COATED ELECTRODES, Electrode, , E, , First, digit, , First two digits indicate, tensile strength of the, deposited weld metal, in 1000 PSI, , Third digit indicates, the welding, positions for electrodes., 1 All position, 2 Flat & horizontal, 3 Flat & down hand, , 262, , Second, digit, , Third, digit, , Fourth, digit, , Fourth digit (0 to 8) indicate, the type of flux coating., 0 Cellulose sodium, or iron oxide mineral, 1 Cellulose potassium, 2 Titania sodium, 3 Titania potassium, 4 Iron powder titania, 5 Low hydrogen lime - sodium, 6 Low hydrogen lime - potassium, 7 Iron oxide plus iron powder, 8 Low hydrogen lime plus iron powder, 9 A number left over for peculiar coating., This number is rarely used., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence
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FOUR DIGITS CODIFICATION, EXAMPLE : AWS – E 6013., , Electrode, , *, , E, , 6, , Tensile strength, 60,000 psi, , 0, , All position, electrode, , 1, , 3, , Titania potassium, , FIVE DIGITS CODIFICATION, , Electrode, , E, 1, , *, , Tensile strength, 110,000 psi., , All position, electrode, , Low hydrogen lime, plus iron powder, , 1, 0, , 1, , 8, , * To get the tensile strength of the weld in p.s.i., the number given, here should be multiplied by 1000., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 263
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CHART 2 (BS 639 : 1976 equivalent to ISO 2560), COVERING 4, A, AR, B, C, O, R, RR, S, , STRENGTH 2, Electrode, designation, , Tensile, strength, N/mm2, , E43, E51, , 430.550, 510.650, , Example (b), , Minimum yield, stress. N/mm2, , 5, % recovery, to nearest, 10% (> 110), (H) 8, Indicates, hydrogen, controlled, (> 15mg/100g), , 330, 360, , E, , 51 33 B, , 1, , PROCESS, , ELECTRODE, EFFICIENCY, , Acid (iron oxide), Acid (rutile), Basic, Cellulosic, Oxidising, Rutile (medium coated), Rutile (heavy coated), Other types, , 2, , 3, , 160, 4, , 2, , 0, , 5, , 6, , (H), 7, , 8, , 1, Covered, MMA, electrode, , WELDING POSITION 6, 1, 2, 3, 4, 5, , All positions, All positions except vertical down, Flat and, for fillet welds, horizontal vertical, Flat, Flat, vertical down and, fot fillet welds, horizontal, vertical, Any position or combination of positions not, classified above., , 6, ELONGATION 3, First, Digit, 0, 1, 2, 3, 4, 5, , Minimum, elongation, %, E43 E51, Not specified, 20, 18, 22, 18, 24, 20, 24, 20, 24, 20, , Temperature for, impact value of, 28J, 0 C, , CURRENT / VOLTAGE 7, Code, , digit, 0, 1, 2, 3, 4, 6, 264, , Impact properties, , elongation, % Impact value, J, , Tempera-, , E43, , ture 0 C, , E51 E43, , Not specified, 22, 22, 22, 22, 22, 22, Not, 18, relevant 18, , Alternating current, , Recommended, electrode, polarity, , Minimum open, circuit voltage,, V., Not suitable, for use on A C, , 0, , Polarity as, recommended, by manufacturer, , 1, 2, 3, , + or +, , 50, 50, 50, , 4, 5, 6, , + or +, , 70, 70, 70, , 7, 8, 9, , + or +, , 90, 90, 90, , Not specified, + 20, 0, -20, -30, -40, , IMPACT 3, Second Minimum, , Direct current, , E51, , Not specified, 47, 47, 47, 47, 47, 47, Not, 41, relevant 47, , +20, 0, - 20, - 30, - 50, , Copyright Free Under CC BY Licence
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Example (1), , Covered electrode for manual metal arc welding having a rutile covering of medium thickness and, depositing weld metal with the following minimum mechanical properties. (BS 639), , Tensile Strength : 500 N/mm 2, Elongation : 23 %, Impact strength : 71J at + 20 0 C, 37 J at 0 0 C, 20 J at -20 0 C., It may be used for welding in all positions. It welds satisfactorily on alternating current with a minimum open-circuit voltage, of 50 V and on direct current with positive polarity., The complete classification for the electrode would therefore be, , E, , 43, , 21, , R, , 1, , 3, , and the compulsory part would be E 43 21R., Covered electrode for manual metal arc welding, Tensile strength, Elongation and impact strength, Covering, Welding positions, Current and voltage, Example (2), , An electrode for manual metal arc welding having a basic covering, with a high efficiency and depositing, weld metal containing 8 ml of diffusible hydrogen per 100 g of deposited weld metal with the following, minimum mechanical properties., , Yield stress: 380 N/mm2, Tensile strength : 560 N/mm2, Elongation : 22 %, , Also a minimum elongation of 20%, , Impact strength : 47 J at -20 0 C, , with an impact value of 28 J at -20 0 C, , Nominal efficiency : 158%, It may be used for welding in all positions except vertical down, direct current only., The complete classification for the electrode would, therefore, be E, , 51, , 33, , B, , 160 2, , 0, , (H), , and the compulsory part would be E 51 33 B.., Covered electrode for manual metal arc welding, Tensile strength and yield stress, Elongation and impact strength, Covering, Efficiency, Welding positions, Current and voltage, Hydrogen controlled, , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 265
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Selection and storage of electrodes, Objectives: At the end of this lesson you shall be able to, • select a suitable electrode to weld a particular job, • state the necessity of baking a coated electrode, • store and handle the electrode properly for better weld quality., Selection/choice of electrodes, Selection of an electrode is very important in order to get, a joint welded with the required strength., Selection factors, Properties of base metal: Top quality weld should be as, strong as the base metal., Select an electrode that is recommended as per the, properties of the base metal. (Fig 1), , Welding position: Electrodes are manufactured for different positions, to produce better welds., Select an electrode as per the welding position. (Fig 3), , The size of the electrode depends on:, – thickness of metal to be welded, – edge preparation of joints, , Welding current: Electrodes are available for use with:, – AC or DC (straight or reverse polarity), , – root run, intermediate or covering run, , – AC and DC (both)., , – welding position, Select as per the availability of the welding machine., , – welder’s skill., Never use a larger dia. electrode than the thickness of base, metal., Joint design and fit up, , Production efficiency: The deposition rate of electrode is, important in production work. So select an iron powder, electrode for production work., Faster the weld, lower the cost., , Select:, – deep penetration electrodes for insufficiently bevelled, joints, – medium penetration electrodes for open and sufficiently, bevelled joints. (Fig 2), , Select the electrode, which is designed for the particular, production work., Usage and storage of electrodes, Electrodes are costly, therefore, use and consume every, bit of them., Do not discard STUB ENDS more than 40-50 mm length., (Fig 4), , 266, , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence
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Storage of electrodes: The efficiency of an electrode is, affected if the covering becomes damp., – Keep electrodes in unopened packets in a dry store., – Place packages on a duckboard or pallet, not directly, on the floor., Electrode coating can pick up moisture if exposed to, atmosphere., Store and keep the electrodes (air tight) in a dry place., Heat the moisture affected/prone electrodes in an electrode, drying oven at 110 - 150° C for one hour before using., (Fig 5), , – Store so that air can circulate around and through the, stack., – Do not allow packages to be in contact with walls or, other wet surfaces., – The temperature of the store should be about 50C higher, than the outside shade temperature to prevent, condensation of moisture., – Free air circulation in the store is as important as, heating. Avoid wide fluctuations in the store temperature., – Where electrodes cannot be stored in ideal conditions, place a moisture-absorbent material (e.g silica-gel), inside each storage container., Drying electrodes: Water in electrode covering is a, potential source of hydrogen in the deposited metal and, thus may cause:, – Porosity in the weld, – Cracking in the weld., Indications of electrodes affected by moisture are:, – White layer on covering., , Remember a moisture-affected electrode:, , – Swelling of covering during welding., – Disintegration of covering during welding., , – has rusty stub end, , – Excessive spatter., , – has white powder appearance in coating, , – Excessive rusting of the core wire., , – produces porous weld., Always pick up the right electrode that will provide:, – good arc stability, – smooth weld bead, , Electrodes affected by moisture may be dried before use, by putting them in a controlled drying oven for approximately, one hour at a temperature around 110 - 1500C. This should, not be done without reference to the conditions laid down, by the manufacturer. It is important that hydrogen controlled, electrodes are stored in dry, heated conditions at all times., , – fast deposition, – minimum spatters, – maximum weld strength, , Warning: Special drying procedures apply to, hydrogen controlled electrodes. Follow the, manufacturer's instructions., , – easy slag removal., , P&M : Fitter - Related Theory for Exercise 1.4.59, , Copyright Free Under CC BY Licence, , 267
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Production & Manufacturing, Fitter - Welding, , Related Theory for Exercise 1.4.60, , Safety precautions in handling gas cutting plant, Objectives: At the end of this lesson you shall be able to, • State the general safety precautions in oxy-acetylene plants., • State the safety rules for handling gas cylindedrs, • State the safety practices for handling gas regulators and hose-pipes., • State the safety precautions related to blow pipe operations., • State the safety required during gas cutting operation., To be accident-free, one must know the safety rules first, and then practise them as well. As we know can accident, starts when safety ends., Ignorance of rules is no excuse!, In gas welding, the welder must follow the safety precautions, in handling gas welding plants and flame-setting to keep, himself and others safe., Safety precautions are always based on good common, sense., The following precautions are to be observed, to keep a gas, welder accident-free., , Even a small leakage can cause serious accidents, , General safety, , Always keep fire-fighting equipment handy and in working, order to put out fires. (Fig 3), , Do not use lubricants (oil or grease) in any part or assembly, of a gas welding plant. It may cause explosion., Keep all flammable material away from the welding area., Always wear goggles with filter lens during gas welding., (Fig 1), Always wear fire resistant clothes, asbestos gloves and, apron., , Keep the work area free from any form of fire., Safety gas Cylinders, Do not roll gas cylinders or use them as rollers., Use a troiley to carry the cyclinders., Close the cylinder valves when not in use or empty., Keep full and empty cylinders separately., Always open the cylinder valves slowly, not more than one, and a half turn., Use the correct cylinder keys to open the cylinders., , Never wear nylon, greasy and torn clothes while welding., Whenever a leakage is noticed rectify it immediately to, avoid fire hazards (Fig 2), , Do not remove the cylinder keys from the cylinders while, welding. It will help to close the cylinders QUICKLY in the, case of a back-fire or flash-back, Always use the cylinders in an upright position for easy, handling and safety., , 268, , Copyright Free Under CC BY Licence
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Always crack the cylinder valves to clean the valve sockets, before attaching regulators (Fig 4), , Always use a black hose pipes for oxygen and maroon, hosepipes for acetylene., Safety for regulators, Safety for rubber hose pipes (Fig 5), , Prevent hammer blows to the gas cyclinders and ensure, that water, dust and oil do not settle on the cylinders., , Inspect the rubber hose pipes periodically and replace the, damaged ones., , One right hand threaded connection for oxygen and left, hand threaded connection for acetylene., , Do not use odd bits of hose pipes / tubes., , Safety for blowpipes, , Do not replace the hose pipes for acetylene with the ones, used for oxygen., , When a blowpipe is not in use put out the flame and place, the blowpipe in a safe place., When flame snaps out and backfires, quickly shut both the, blowpipe valves (oxygen first) and dip in water., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence, , 269
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Method of handling cutting torch-description, parts, function and uses, Objectives: At the end of this lesson you shall be able to, • explain the principle of gas cutting, • describe the cutting operation and its application., Introduction to gas cutting : The most common method, of cutting mild steel is by an oxy-acetylene cutting process. With an oxy-acetylene cutting torch, the cutting, (oxidation) can be confined to a narrow strip and with little, effect of heat on the adjoining metal. The cut appears like, a saw-cut on a wooden plank. The method can be successfully used to cut ferrous metals i.e. mild steel., Non-ferrous metals and their alloys cannot be cut by this, process., , Also the iron oxide is in molten condition called slag. So the, jet of oxygen coming from the cutting torch will blow the, molten slag away from the metal making a gap called 'Kerf'., Fig.2, Cutting operation (Fig 2): There are two operations in, oxy-acetylene gas cutting. A preheating flame is directed, on the metal to be cut and raises it to bright red hot or, ignition point (900°C app.). Then a stream of high pressure, pure oxygen is directed on to the hot metal which oxidises, and cuts the metal., , Principle of gas cutting: When a ferrous metal is heated, to red hot condition and then exposed to pure oxygen, a, chemical reaction takes place between the heated metal, and oxygen. Due to this oxidation reaction, a large amount, of heat is produced and cutting action takes place., , When a piece of wire with a red hot tip is placed in a, container of pure oxygen, it bursts into flame immediately, and is completely consumed. Fig 1 illustrates this reaction. Similarly in oxy-acetylene cutting the combination of, red hot metal and pure oxygen causes rapid burning and, iron is changed into iron oxide (oxidation)., By this continuous process of oxidation the metal can be, cut through very rapidly., The iron oxide is less in weight than the base metal., , 270, , The two operations are done simultaneously with a single, torch., The torch is moved at a proper travel speed to produce a, smooth cut. The removal of oxide particles from the line of, cut is automatic by means of the force of oxygen jet during, the progress of cut., 300 litres of oxygen are required to oxidize one, kilogram of iron completely. The ignition temperature of steel for gas cutting is 875°C to, 900°C., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence
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Application of cutting torch: Oxy-acetylene cutting, torch is used to cut mild steel plates above 4mm thickness., The M.S plate can be cut to its full length in straight line, either parallel to the edge or at any angle to the edge of the, plate. Bevelling the edges of a plate to any required angle, can also be done by tilting the torch. Circles and any other, curved profile can also be cut using the cutting torch by, using a suitable guide or template., Fig.3 to Fig.7 shows the guides used to cut straight lines,, bevel and small circles., , Cutting torch guides: Guides are sometimes used during, oxy acetylene cutting., They can be either a roller guide, double support or spade, guide with single support., , Cutting guides are held onto the nozzle of the cutting torch, by tightening a clamp bolt. The clamps, where they are, fitted, are adjusted so the inner cones of the preheat flames, are approximately 2-3mm above the surface of the metal to, be cut. The tip of the cutting nozzle is held at distance of, 5-6mm above surface of the plate being cut., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence, , 271
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Oxy-acetylene cutting equipment, Objectives: At the end of this lesson you shall be able to, • explain the features of the oxy-acetylene cutting equipment, its parts and cutting torch, • describe the oxy-acetylene cutting procedure, • differentiate between cutting and welding blowpipes., Cutting equipment: The oxy-acetylene cutting equipment, is similar to the welding equipment, except that instead of, using a welding blowpipe, a cutting blowpipe is used. The, cutting equipment consists of the following., – Acetylene gas cylinder, – Oxygen gas cylinder, – Acetylene gas regulator, – Oxygen gas regulator (Heavy cutting requires higher, pressure oxygen regulator.), – Rubber hose-pipes for acetylene and oxygen, – Cutting blowpipe, (Cutting accessories i.e. cylinder key, spark lighter, cylinder, trolley and other safety appliances are the same as are, used for gas welding.), The cutting torch (Fig 1): The cutting torch differs from the, regular welding blowpipe in most cases; it has an additional, lever for the control of the cutting oxygen used to cut the, metal. The torch has the oxygen and acetylene control, valves to control the oxygen and acetylene gases while, preheating the metal., , Oxy-acetylene cutting procedure: Fix a suitable size, cutting nozzle in the cutting blowpipe. Ignite the cutting, torch the same way as was done in the case of the welding, blowpipe. Set the neutral flame for preheating. To start the, cut, hold the cutting nozzle at angle 90° with the plate, surface, and the inner cone of the heating flame 3 mm, above the metal. Preheat the metal to bright red before, pressing the cutting oxygen lever. If the cut is proceeding, correctly, a shower of sparks will be seen to fall from the, underside of the plate. Move the torch steadily on the, punched line. If the edge of the cut appears to be too, ragged, the torch is being moved too slowly. For a bevel, cut, hold the cutting torch at the desired angle and proceed, as is done in making a straight line cut. At the end of the, cut, release the cutting oxygen lever and close the control, valves of the oxygen and acetylene. Clean the cut and, inspect., Difference between cutting blowpipe and welding, blowpipe: A cutting blowpipe has two control valves, (oxygen and acetylene) to control the preheating flame and, one lever type control valve to control the high pressure pure, oxygen for making the cut., A welding blowpipe has only two control valves to control, the heating flame. (Fig 2), , The nozzle of the cutting blowpipe has one hole in the, centre for cutting oxygen and a number of holes around the, circle for the preheating flame. (Fig 3), , The cutting tip is made with an ORIFICE in the centre, surrounded by five smaller holes. The centre opening, permits the flow of the cutting oxygen and the smaller holes, are for the preheating flame. Usually different tip sizes are, provided for cutting metals of different thicknesses., , 272, , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence
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The nozzle of the welding blowpipe has only one hole in the, centre for the heating flame. (Fig 4), , The angle of the welding nozzle with the neck is 120°., The cutting nozzle size is given by the diameter of the, cutting oxygen orifice in mm., The welding nozzle size is given by the volume of oxyacetylene mixed gases coming out of the nozzle in cubic, meter per hour., Operating data for cutting mild steel, , The angle of the cutting nozzle with the body is 90°., Cutting nozzle, size - mm, , Thickness of plate (mm), , Cutting oxygen, pressure Kgf/cm2, , 0.8, , 3-6, , 1.0 - 1.4, , 1.2, , 6 - 19, , 1.4 - 2.1, , 1.6, , 19 - 100, , 2.1 - 4.2, , 2.0, , 100 - 150, , 4.2 - 4.6, , 2.4, , 150 - 200, , 4.6 - 4.9, , 2.8, , 200 - 250, , 4.9 - 5.5, , 3.2, , 250 - 300, , 5.5 - 5.6, , Care and maintenance: The high pressure cutting oxygen lever should be operated only for gas cutting purposes., Care should be taken while fitting the nozzle with the torch, to avoid wrong thread. Dip the torch after each cutting, operation in water to cool the nozzle., To remove any slag particles or dirt from the nozzle orifice, use the correct size nozzle cleaner Fig.5. Use an emery, paper if the nozzle tip is damaged to make it sharp and to, be at 900 with the nozzle axis., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence, , 273
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Oxy-acetylene hand cutting - piercing hole and profile cutting, Objectives: At the end of this lesson you shall be able to, • explain the special types of nozzles for gas cutting and their application, • describe the parts of a cutting equipment and their functions, • explain troubleshooting and the remedy of the faults in oxygen cutting., Table of some common cutting torch tips and their uses, Number of preheat orifices in, cutting torch tips, , 274, , Degree of, preheating, , Application, , Medium, , For straight line or circular cutting, of a clean plate., , Light, , For splitting angle iron, trimming plates, and sheet metal cutting., , Light, , For hand cutting rivet heads and, machine cutting 30 deg. bevels., , Light, , For straight line and shape cutting, clean plate., , Medium, , For rusty or painted surfaces., , Heavy, , For cast iron cutting and preparing, Vee for cast iron welding ., , Very, heavy, , For general cutting; also for cutting, and stainless steel., , Medium, , For grooving, flame machining, gouging, and removing imperfect welds., , Medium, , For grooving, gouging or removing, imperfect welds., , Medium, , For machine cutting 45° deg. bevel or, hand cutting rivet heads., , Heavy, , Flared cutting orifices provide a large, oxygen stream of low velocity for rivet, head removal (washing)., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence
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Special purpose nozzle: For profile cutting, different, types of nozzles are used for cutting metals in different, shapes., Nozzles used for cutting profiles are shown in Fig 1., , Names and functions of the parts of a cutting torch (Fig, 3 and Table 1), Table 1, Cutting torch: Fig 2 Oxygen and fuel gas are mixed and, then the gas is carried to the tip of the orifice to form, ‘preheat’ flames. If oxygen is carried directly to the tip it, oxidises the metal and blows it away to form the cut., Method of piercing a hole: Hold the cutting blowpipe at, right angles on the point where the hole is to be made. The, point will be brightened. Release the cutting oxygen, slowly. Raise the torch, tilt the nozzle slightly to the left, and right directions so that the sparks may not foul the, nozzle. Thus the hole may be pierced., For cutting of the profile hold the blowpipe head in such a, way that the oxygen stream is directed by the correct tilting, of the blowpipe. It is obvious that the angle between the, nozzle and the plate must remain constant and this poses, the greatest difficulty for the beginners., Position of the preheating flame as related to the plate, surface is very important., , No., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, , Name, Acetylene, gas valve, Oxygen, hose joint, Acetylene gas, hose joint, Oxygen conduit, Acetylene gas, conduit, Grip, Preheating, oxygen valve, Cutting oxygen, valve, Injector, Cutting oxygen, conduit, Mixed gas, conduit, Torch head, , Function, To adjust the flow rate, of acetylene gas., To connect with the, oxygen hose., To connect with the, acetylene gas hose., To lead oxygen., To lead acetylene gas., To hold the torch., To adjust the preheating, flame., To adjust the cutting, oxygen flow rate., To mix the acetylene gas, with oxygen., To lead the cutting oxygen., To lead the mixture of, acetylene gas and oxygen., To attach the nozzle., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence, , 275
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Troubleshooting, Object, , Trouble, , Part to be, checked, , Method, , Hose joint, , Soap water, or water, , Tighten further, or replace., , At the beginning of the, work., , Valve &, regulator, , Soap water, or water, , Replace the torch., , At the beginning of the, work., , Cutting, tip attaching part, , Soap water, or water, , Tighten further, or replace., , At the beginning of the, work., , Injector, , Plug the fuel, gas hose mouth, with your finger., , Replace., , Periodical check for the, low pressure torch., , Preheating, flame shape, , Neutral flame by, visual inspection, , Clean or replace., , At the beginning of the, work or at random., , Cutting oxygen flow, , Visible gas flow by Clean or replace., visual inspection, , At the beginning of the, work or at random., , Gas leakage, Torch, , Suction of, Acetylene, , Care and maintenance: The cutting oxygen orifice, should be cleaned at regular intervals by using different, size wire of nozzle cleaner. (Fig 4), , Remedy, , Characteristics of analysis of cutting: This analysis has, been made on referring to the cutting face and the formation, of cut in this surface., This can be analysed as shown in the figure . (Fig 5), , Safety in gas cutting process, Objectives: At the end of this lesson you shall be able to, • describe the safety precautions to be followed for handling gas cutting equipment, • explain the safety precautions to be followed by the operator, • state the safety required during gas cutting operation., Equipment safety: Safety precautions for gas cutting, equipment are the same as those adopted in the case of, gas welding equipment., , 276, , Safety for the operator (Fig 1), Always use safety apparel for the:, , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence
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In case the flammable material is difficult to remove,, suitable fire resisting guards/partitions must be provided., Protect yourself and others from the flying sparks., Ensure that the metal being cut is properly, supported and balanced so that it will not fall, on the feet of the operator or on the hoses., Keep the space clear underneath the cutting job so as to, allow the slag to run freely, and the cutting parts to fall, safely., Be careful about flying hot metal and sparks while starting, a cut. Containers which hold combustible substances, should not be taken directly for cutting or welding. (Fig 2), Wash the containers with carbon tetrachloride and caustic, soda before welding or cutting and fill them with water, before repairing., Keep fire-fighting equipment handy and ready., , –, –, –, –, , protection of your eyes, protection from burns, protection of clothing, prevention of inhaling burnt gases., , Goggles, gloves and other protective clothing must be, worn., Safety during operation: Keep the work area free from, flammable materials., Ensure that the combustible material is atleast, 3 metres away from the cutting operation area., , Common faults in gas cutting, Objectives: At the end of this lesson you shall be able to, • explain the common faults in cutting, • describe the causes and remedies, • explain the method of good gas cutting., Common faults in cutting, (Fig 1) The tip is too high off the steel. The top edge is, heated or rounded, the cut face is not smooth, and often the, face is slightly bevelled where preheat effectiveness is, partially lost due to the tip being held so high. The cutting, speed must be reduced because of the danger of losing the, cut., (Fig 2) Extremely slow cutting speed. Pressure marks on, the cut face indicate too much oxygen for the cutting, conditions. Either the tip is to big, the cutting oxygen, pressure is too high, or the speed is too slow as shown by, , the rounded or beaded top edge. On reducing the cutting, oxygen volume to the correct proportions for the thickness, of the cut, the pressure marks will recede toward the, bottom edge until they finally disappear., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence, , 277
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(Fig 3) Tip too close to the steel. The cut shows grooves, and deep drag lines, caused by an unstable cutting action., Part of the preheat cones burned inside the kerf, where, normal gas expansion affected the oxygen cutting stream., , (Fig 4) Too much cutting oxygen. The cut shows pressure, marks caused by too much cutting oxygen. When more, oxygen is supplied than can be consumed in oxidation, the, remainder flows around the slags, creating gouges or, pressure marks., , (Fig 5) Too much preheating. The cut shows a rounded top, edge caused by too much preheat. Excess preheating, does not increase the cutting speed, it only wastes gases., , (Fig 8) Slightly too slow a cutting speed. The cut is of high, quality although there is some surface roughness caused, by the vertical drag line. The top edge is usually slightly, beaded. This quality is generally acceptable, but faster, speeds are more desirable because the labour cost for this, cut is too high., , In a good cut, the edges are square, and the lines of cut are, vertical. (Fig 9), , (Fig 6) Poor quality bevel cut. The most common fault is, gouging, caused by either excessive speed or inadequate, preheat flames. Another fault is a rounded top edge caused, by too much preheat, indicating excessive gas consumption., (Fig 7) Slightly too fast a cutting speed. The drag lines on, this cut incline backwards, but a ‘drop cut’ is still attained., The top edge is good; the cut face is smooth and slag-free., This quality is satisfactory for most production work., 278, , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence
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Gas cutting machines (oxy-acetylene), Objective : At the end of this lesson you shall be able to, • identify the different types of gas cutting machines., Straight line and circle cutting machines, These machines are used for regular, straight and circle, cutting., Straight line cutting (Fig 1), , Large circle cutting (Fig 2), , Small circle cutting (Fig 3), Profile cutting machines, , It is also called as radial arm cutting machine., , These are used to cut any shape required for fabrication., , A profile cutting machine with a magnetic roller for multicutting heads is shown in Fig 5., , A profile cutting machine with magnetic roller for single, cutting head is shown in Fig 4., , It is also called as cross-carriage cutting machine., Profile cutting machines are also available with an electronic, control and scanning head., , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence, , 279
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Pipe cutting machines, These are used for circumferential cutting or beveling of, pipes., A simple pipe cutting arrangement using a hand cutting, blowpipe is shown in Fig 7., , Electronic control replaces the magnetic roller system and, template. (Fig 6), , The pipe is rotated by hand., The pipe cutting machine with manual control shown in, Fig 8 is rotated by hand around the pipe., , 280, , P&M : Fitter - Related Theory for Exercise 1.4.60, , Copyright Free Under CC BY Licence
